In Oregon, rose leaves held up to the light in late spring can glow as if someone had scraped off the green with a fingernail. Those pale, papery patches usually mean roseslugs, small larvae that feed on the underside of the leaf.

Roseslugs (sawfly larvae): What You See

The damage shows up before the pest does, so start with the leaf and then turn it over.

• Windowpane patches, small areas of thin, papery leaf tissue you can nearly see through, are the sign that sets roseslugs apart from other leaf chewers.
• Held up to the sun, an affected leaf lets light shine through the scraped areas.
• Small, wormy, slug-like larvae sit beneath the leaves, and they are easy to miss.
• Larvae of the bristly kind are about 5/8″ long, greenish-white, with long, stout bristles.
• In heavy infestations, leaves skeletonized down to the veins can turn brown and curl.
• In Maryland, the greenish-yellow larvae are worth looking for in May and June, and in Kentucky the first damage appears in April.

Early damage can look like tiny clear patches, so check the undersides before the leaf looks ragged.

Roseslugs (sawfly larvae) or Something Else?

Several leaf problems on roses leave ragged or discolored foliage, and a quick look is not enough to separate them. Pair what the leaf looks like with what you find on its underside.

Black spot and powdery mildew are diseases, while aphids are sap-feeding insects, so none of them scrape leaves into skeletons.

Looks like	How to tell them apart
Black spot	Dark blotches on the leaf surface, with no clear papery windows and no larvae underneath
Powdery mildew	A dusty coating on the leaf, and the tissue stays intact rather than thinning to see-through patches
Aphids	Clusters of small sap feeders on new growth, with no veins left behind after feeding

Roseslug damage is the one that leaves the veins standing and the tissue between them thin as paper. If you see that pattern together with small larvae below, you have sawflies.

What Causes Roseslugs (sawfly larvae), and Where It Is Worst

These are insect larvae, not true slugs, and they belong to the sawflies. An adult female lays eggs on rose stems and leaves, and the eggs hatch into the little larvae that do all of the feeding. Bristly roseslug females insert eggs into the leaf stalks in three rows.

Once the tiny larvae hatch, they move to the underside of the leaf and feed on its surface layer. Fully grown larvae drop from the plant and pupate in a cocoon in the soil.

Timing depends on where you garden. In Oregon, the common roseslug skeletonizes leaves in late spring and early summer. The common roseslug has one generation and the curled roseslug two, so the damage in Ohio was fleeting and roses recovered without spraying even with high populations. Kentucky and Maryland describe a longer season, with activity into the fall in Maryland. Roses of every type are fair game.

How to Treat Roseslugs (sawfly larvae)

Treatment starts with finding the larvae, since they hide under the leaves.

1. Turn leaves over and look underneath regularly, so that you catch the larvae while the damage is still small patches.
2. Pick off the larvae you find by hand.
3. Check badly skeletonized leaves and remove the larvae you find.
4. Keep watching, because there may be several generations a year in some places and new larvae can follow the first group.
5. Get local advice before using any spray, so that you choose a product approved where you live.

Where only one or two generations occur, as in Ohio, roses have recovered on their own without spraying, so a light infestation is no reason to rush.

How to Prevent Roseslugs (sawfly larvae) Coming Back

Prevention follows the insect’s year: eggs on the plant, larvae on the leaf, cocoons in the soil.

• In Kentucky, start checking leaf undersides in April, when damage may first appear.
• In Oregon and Maryland, look closely in May and June for early feeding and larvae.
• Through summer, keep monitoring, since later generations may follow in places with more than one.
• In the fall, keep looking where roseslugs stay active, as they do in Maryland.
• Keep checking leaf undersides so you can remove larvae before they drop to the soil to pupate.

Roseslugs can also be reported on strawberries and raspberries, so check those plants nearby too.

Where This Comes From

The timing here varies among Oregon, Ohio, Kentucky and Maryland. Timing differs from state to state, so seek local advice about dates and approved treatments.

Common Questions

Are Roseslugs Actually Slugs?

No. They are insect larvae in the sawfly group, not slugs.

Will Roseslugs Kill a Rose?

In Ohio, roses recovered without spraying even when populations were high because the damage was brief in spring.

Do Roseslugs Prefer Certain Roses?

They do not discriminate on the type of rose they feed on, so any rose in the yard can be affected.

Run a hand along a bare rose cane in winter and you may find small gray-white crusts that look like flecks of old paint. Those crusts are rose scale, an insect that spends nearly its whole life stuck in place, feeding on sap. Knowing what the crusts look like, and when the insect moves, tells you when to act.

Rose Scale: What You See

Look on the canes first, since that is where this insect settles and feeds.

• Round, gray to white crusts on the canes are the females, each about 1/16 inch long.
• Much smaller, narrow white shapes among them are the males, which are elongate rather than round.
• In Virginia, orangish crawlers wander over the bark after temperatures warm in spring, before they settle and begin to build a covering.
• Leaves that yellow or wilt, and growth that looks stunted, show up when the canes are heavily coated.
• A sticky film on the lower leaves, often turning black with sooty mold, comes from the honeydew the insects leave behind.

A cane that looks crusty and a plant that looks tired on the same bush point to scale rather than a passing stress.

Rose Scale or Something Else?

Several rose problems leave marks on leaves and stems that get blamed on scale. A quick look at the canes and the leaves together sorts most of them out.

Sooty mold and plain plant stress are the usual mix-ups, and both can sit on a bush that has scale as well.

Looks like	How to tell them apart
Sooty mold, a black film on lower leaves	Scale is behind it when the leaves feel sticky and ants are around, and gray-white crusts sit on the canes above.
Yellowing or wilting leaves from plain stress	Scale is likely when the canes carry round crusts and the stunting follows the crusty stems rather than the whole plant.

In California, San Jose scale is a different armored scale that can also attack roses.

What Causes Rose Scale, and Where It Is Worst

The cause is the insect’s own life cycle. Females lay eggs under the waxy covering of the mother, and the eggs overwinter there, protected on the cane. In Virginia, the crawlers roam freely after temperatures warm in spring, then settle to feed.

Once a crawler settles, it loses its legs and antennae and stays put. Older nymphs begin secreting the waxy cover that makes the insect hard to reach. Adult males are tiny and winged, so they fly in search of females, while the females stay under their scales until they lay eggs and die.

Rose scale is most active in the warmer months. In Virginia, a second generation may appear in August when conditions favor the population. Wherever you garden, check a rose with crusty canes for scale.

How to Treat Rose Scale

Treatment follows the insect’s calendar, because the crawler stage is the one time the insect is mobile and unprotected.

1. Inspect the canes closely in winter, when the leaves are gone, so that every crusty stem is easy to find.
2. In California, cut back and destroy infested canes in winter, which removes eggs sheltered under the covering.
3. Judge the population on the canes that remain. An oil treatment is suggested on remaining infested canes only when the scale population is high.
4. If the population stays high, get local advice before choosing a treatment.
5. In Virginia, watch the canes after temperatures warm in spring, when orangish crawlers wander before settling.
6. Recheck in August, because a second generation may occur in Virginia under good conditions for scale.

Armored scales sit under a hard cover once they settle, so a late treatment reaches less than an early one. Pruned canes should leave the yard rather than sit in a pile near the roses.

How to Prevent Rose Scale Coming Back

Prevention is mostly looking at the right time, since this insect shows itself on the canes before it harms the leaves.

• After leaf drop, check the bare canes for gray-white crusts, because the eggs overwinter under the mother’s covering.
• In Virginia, look for unprotected orangish crawlers moving across the bark after temperatures warm in spring.
• Through the warmer months, glance at the canes regularly, because rose scale is most active then.
• In August, if you garden in Virginia, check again for a second generation on canes that looked clean earlier.
• When lower leaves turn sticky or black at any point in the season, trace the film up to the canes and look for crusts.

A short look at the canes each time you walk past the bed catches the first crusts before they spread.

Where This Comes From

The timing varies by place, so use the state-specific guidance above only where it applies. For dates and approved products that fit your yard, seek local advice.

Common Questions

Can Rose Scale Kill a Rose Bush?

It can. In Iowa, heavy infestations are described as causing death of all or part of the plant, and in California, high numbers may cause cane decline or dieback.

Do Rose Scale Insects Move from Plant to Plant?

The crawlers wander freely over the bush before settling, and adult males are winged and can fly in search of females. The adult females stay put under their scales.

What Do Rose Scale Eggs Look Like?

The eggs are reddish-orange, and they sit hidden under the waxy covering of the mother. This is how the insect gets through winter on the cane.

Rose buds that turn black at the tip and never open are a sign worth checking on before you blame the weather. Tiny flies called rose midges lay eggs in new growth, and their larvae do the damage from inside. The pest is uncommon, but where it settles, it can wreck a flush of bloom.

Rose Midge: What You See

Damage on new growth is often easier to spot than the insect, so start with the buds and shoot tips.

• Flower buds come out distorted, bent or misshapen, and some never open at all.
• Shoot tips and bud tips turn black, then wither and die back.
• Injured buds may turn brown or black and drop off before they are fully formed.
• Inside the sepals and the tight new growth, tiny white maggots feed, and in California they grow to only 1/16 inch long.
• The adults are very tiny flies, easy to miss around the plant.

Damage usually appears in July in Illinois, while Oregon and North Carolina report other local timing patterns.

Rose Midge or Something Else?

Blackened, deformed buds can have other causes, so look at the larvae and the pattern of damage together. A hand lens helps, since the maggots are so small.

Rose curculio can look similar because its larvae resemble those of the rose midge.

Looks like	How to tell them apart
Rose curculio damage	Rose midge larvae are tiny white maggots, but appearance alone may not separate them from rose curculio larvae.
Buds that fail to form for other reasons	Deformed buds alone prove nothing. Check whether the tips are also blackening and withering, and whether maggots are inside the sepals.

Rose midge damages developing buds and plant terminals.

What Causes Rose Midge, and Where It Is Worst

The cause is a tiny fly, Dasineura rhodophaga. In North Carolina, adults emerge from pupae in the soil early in spring, about when roses begin new growth. Females lay eggs inside the sepals of new flower and leaf buds, and the maggots that hatch feed there.

Several generations can occur in a year, since 2 to 4 generations can occur annually. Damage tends to increase through the season.

The pest is established in Oregon and Washington, and it can be severe there. In Oregon, sampling in 2004 found two peaks of damage, in late June and early July and again in late August and early September. North Carolina reports a similar pattern, with peaks in late June and late August. Maryland describes it as uncommon but possible in rose plantings. In California it was found in a Petaluma nursery in August 1996 and has not been reported since, so it is rarely a problem there.

How to Treat Rose Midge

Treatment starts with removing the infested tissue, because the maggots live inside it.

1. Inspect new buds and shoot tips for blackened tissue and distortion.
2. Prune out blackened, distorted buds and withered tips, so that the maggots inside are removed from the plant.
3. Damage tends to increase through the season.
4. If the problem persists, insecticide may be needed.

Control includes pruning out damaged buds. If the problem persists after pruning, insecticide may be needed.

How to Prevent Rose Midge Coming Back

Rose midges emerge from the soil about when roses start new growth.

• In North Carolina, begin checking buds and shoot tips in early spring as new growth starts.
• Look closely at new shoots in late June in North Carolina and in late June and early July in Oregon.
• Check for another peak in late August in North Carolina and in late August and early September in Oregon.
• Whenever you buy new roses, inspect the plants for blackened tips and distorted buds before planting, since the pest can arrive on nursery stock.

Where This Comes From

Common Questions

Can Rose Midge Kill a Rose Bush?

Rose midge damages buds and shoot tips, causing blackened tissue and tip abortion. Repeated damage can still cost you bloom.

Where Do Rose Midges Spend the Winter?

Pupation happens in the soil; in North Carolina, the midges emerge early in spring, about when roses start new growth.

Should You Worry About Rose Midge in California?

It was found in a Petaluma nursery in August 1996 and has not been reported in California since, so it is rarely a pest there.

Pale, speckled rose leaves, with tiny wedge-shaped insects flicking away when a cane is touched, usually point to rose leafhoppers. They feed on leaf undersides and lay eggs in the canes, while the wounds they leave can admit fungi that cause stem canker.

Rose Leafhopper: What You See

Start with the insect itself, because the leaf damage alone can fool you.

• The adults are wedge-shaped and between ¼- to ½-inch long, and they hop or fly away quickly when the plant is disturbed.
• The nymphs are white with red eyes, and older ones show rows of dark spots on the back of the thorax.
• Leaves develop white or pale blotches that look like spider mite stippling, only larger.
• Cast skins cling to the underside of the leaves, where the feeding happens.
• Dark, purple, pimple-like spots on the bark mark the places where eggs have been laid.

Heavy feeding can leave leaves browning and dropping, and a sticky honeydew film may grow sooty mold when numbers climb.

Rose Leafhopper or Something Else?

Stippled, blotchy leaves have several culprits, and a single clue is not enough to name one. Look at the underside of the leaf and at the timing before you reach for any treatment.

Leafhoppers are not common problems in most areas, so find the insects themselves before deciding that is what you have.

Looks like	How to tell them apart
Spider mites	Stippling is smaller than leafhopper damage, and webbing shows on the leaf underside, while leafhoppers leave cast skins and no webbing.
Roseslug sawfly	Larvae up to ¾ inches long eat the soft leaf tissue and leave the veins, and damage shows in May and June in Wisconsin.
White apple leafhopper	Adults match in size and color, but this one has two generations a year, while rose leafhopper has three.

Sawfly damage looks like lace, with the veins left standing, which is quite different from the pale flecks of a leafhopper. The adults are the same size and color, and differences in their genitalia distinguish rose leafhoppers from white apple leafhoppers.

What Causes Rose Leafhopper, and Where It Is Worst

The cause is a cycle that starts on the cane. In South Carolina, the adult female lays eggs inside the bark of rose canes in the fall, and in spring the young nymphs emerge from them. That is the pattern described for the species.

Rose is the only plant this leafhopper appears to overwinter on, as described for Washington. During summer generations it can move to other hosts, and the nymphs also feed on dogwood, hawthorn, plum and oak.

Wounds from egg laying and from emerging nymphs can let stem canker fungi in, and stem canker can result in plant death.

How to Treat Rose Leafhopper

Plants tolerate moderate stippling, so begin with the gentlest tools and step up only if the infestation is severe.

1. Check the leaf undersides for insects and cast skins, so that you treat leafhoppers and not a mite problem that looks alike.
2. Knock the insects off with a water spray, since adults and nymphs feed on the undersides.
3. Use an insecticidal soap on the nymphs if the infestation is severe, because the immature stage is the one this treatment is aimed at.
4. Inspect the canes for dark, pimple-like spots that indicate the presence of eggs.
5. Look at the bark for egg-laying wounds, which can provide openings for fungi that cause stem canker.

If sprays are not enough, a garden store product must list leafhoppers on the label and be clearly labeled for roses. Follow the label directions carefully.

How to Prevent Rose Leafhopper Coming Back

In South Carolina, females lay eggs in rose canes in fall and young nymphs emerge in spring.

• In South Carolina, females deposit eggs in the bark in fall; dark, purple spots indicate their presence.
• In South Carolina, watch for wingless nymphs as they emerge from the cane in spring.
• Cast skins on leaf undersides are a useful sign that leafhoppers are present.
• Rinse the leaf undersides with water when you see insects feeding there.
• Nymphs can also feed on dogwood, hawthorn, plum and oak.

Where This Comes From

Common Questions

Do Rose Leafhoppers Kill Roses?

Plants can tolerate moderate stippling. Egg-laying and emergence wounds can admit fungi that cause stem canker, which can result in plant death.

Why Are There Sticky Leaves and Black Film on My Roses?

Leafhoppers secrete honeydew, and with enough of them, sooty mold fungus grows on it. Look under the leaves for the insects or cast skins to confirm the cause.

Can Rose Leafhoppers Live on Other Plants?

Yes. In Washington, the species appears to overwinter only on rose but can use other plants in summer. The nymphs also feed on dogwood, hawthorn, plum and oak.

Ragged holes in rosebuds or buds that never open often point to a small red and black weevil feeding on the plant. Rose curculio feeds on buds, petals and cane tips, and its larvae finish the job from inside the bud. The adult is red and black with a long snout, while the larvae remain hidden inside the bud.

Rose Curculio: What You See

Start with the insect itself, because its colors and snout help distinguish it from other insects on a rose.

• The adult has a bright red back and thorax with a black head that stretches into a long snout.
• It is a hard-bodied beetle about 1/4 inch long, with long black legs and distinct antennae.
• In California, adults drill holes in buds, and flowers that open may have ragged petals.
• Stems may bend over just below a bud that has been fed on, as reported in Minnesota.
• Shoot tips die back, and where weevils are numerous in California, terminal shoots may be killed.
• Buds that never open may hold plump, legless, pale orange to whitish larvae with a brown head.

In California, adults emerge from the soil in spring.

Rose Curculio or Something Else?

The damage is easy to blame on the wrong insect, because chewed buds have more than one culprit. A hole in a bud tells you something ate it. It does not tell you what.

Check the plant itself and the inside of the bud before you decide.

Looks like	How to tell them apart
Earwig feeding, with holes in buds and sometimes young shoots	Rose curculio shows a red and black weevil with a long snout on the bud, and a bud that stays shut may hold a pale larva with a brown head

Raspberries and other caneberries can host the same weevil, so cane fruit growing near the roses is worth a glance when buds look chewed.

What Causes Rose Curculio, and Where It Is Worst

The cause is a weevil with one generation a year. Adults feed on buds, and females lay eggs inside them. The eggs hatch into larvae that keep feeding inside the bud, often killing it before it opens.

Mature larvae drop to the ground and pass the winter as pupae in the soil around the base of the plant. In California, adults emerge from that soil in spring, and the cycle starts again right under the same shrub.

Wild roses are the main host for this native weevil. Garden roses with hips draw adults, and pink and yellow ones are named as favorites. Yellow and white roses are also described as preferred hosts.

How to Treat Rose Curculio

How to Prevent Rose Curculio Coming Back

• In early spring, watch for the first red and black adults as they come out of the soil, since in California that is when they emerge.

Where This Comes From

Wild roses are the main host of this native weevil.

Common Questions

Do Rose Curculios Attack Raspberries Too?

Yes, though less commonly than roses. Both the rose curculio and the western rose curculio feed on caneberries and roses.

How Many Generations of Rose Curculio Are There Each Year?

One. The weevil has a single generation, so the larvae you see in buds will become the adults of next spring.

What Do Rose Curculio Eggs Look Like?

The eggs are oval and about 1/25 inch long. They sit hidden in the bracts and buds of the flowers, so you are far more likely to notice the damage than the eggs.

A rose leaf with a neat, round-edged bite missing from its margin is the signature of a leafcutting bee at work. The cut looks deliberate because it is. The bee carries the piece away to line a nest, and the damage on a healthy rose is usually more curiosity than threat.

Leafcutting Bees: What You See

The clearest sign is on the leaves, and the bee itself is easy to overlook while the cuts are not.

• Smooth half moon or semicircular holes appear along the edge of the leaf, about 3/4 inch across, with a clean cut unlike the ragged edge chewing insects leave.
• Precise ovals or circles may be missing from the foliage, and flower petals can be trimmed the same way.
• Look for holes that begin at the leaf margin rather than in the middle of the blade.
• The bee looks like a honey bee but is often darker in color, and it is seen near the roses while the cutting is going on.
• In Minnesota, the cutting shows up from late May to early June.

Other plants nearby, such as lilac, redbud and ash, can carry the same notches.

Leafcutting Bees or Something Else?

Notched leaves have more than one possible author, and the edge of the cut tells most of the story. A bee removes a clean piece, while chewing insects leave a torn outline.

The bee’s nesting habit gives a second check. Look for a drilled hole in a freshly pruned cane or in nearby soft, rotted wood.

Looks like	How to tell them apart
Leaf-feeding insects	Ragged, uneven edges on the leaf, where the bee’s cut is very smooth and semicircular
Honey bees visiting the flowers	Honey bees are often paler, while leafcutting bees tend to be darker and are the ones leaving round notches on the foliage

Pith-boring insects in cut canes can also be blamed for tunnels, but a bee nest sits inside the pith of a pruned cane and is lined with round pieces of foliage.

What Causes Leafcutting Bees, and Where It Is Worst

The cause is a native solitary bee building nests. Females do not form colonies. Each one excavates a tunnel several inches deep in rotted wood, hollow twigs, bee nest boxes or the pithy stems of thick-caned plants such as roses.

Once the tunnel is ready, she cuts leaf pieces to line individual cells, then stocks each with pollen and nectar for the young. Your rose is simply the source of the lining material.

Damage is more serious in isolated rural plantings, and where the bees are abundant and concentrate on cultivated plantings. On most garden roses, the damage is minor.

How to Treat Leafcutting Bees

Treatment is mostly a matter of deciding whether anything is needed, because the bees pollinate and rarely do major harm. If you want to act, work in this order.

1. Confirm the cut, looking for smooth semicircles at the leaf edge, so that you are not treating a different pest.
2. Leave the bees alone, because they are beneficial pollinators and should not be killed.
3. Skip insecticides, since they are ineffective for preventing leaf cutting and harm helpful insects.
4. Drape cheesecloth or other loose netting over the roses during the weeks when the bees are most active, so that they cannot reach the leaves.
5. Keep the plant healthy with good culture, so that it tolerates the lost tissue easily.

Netting is the only known control for leaf injury. In most yards the notched leaves are an aesthetic blemish that harms no otherwise healthy plant.

How to Prevent Leafcutting Bees Coming Back

Prevention is limited, but a few timed habits reduce nesting in your canes and keep the plants strong.

• Whenever you prune, seal the cut ends of canes with wax or a couple drops of white glue.
• Before late May, have netting ready if you want to protect prized plants, since in Minnesota the cutting begins then.
• Through the growing season, water and feed regularly so the plant stays healthy enough to shrug off notches.
• Whenever you prune later in the year, seal those fresh cane ends again so bees cannot excavate the pith.
• In fall cleanup, leave sprays in the shed, since pesticides harm the bees you want to keep.

Sealing matters because bees excavate the pith of pruned canes, though the largest canes suffer little since tunneling rarely girdles the cambium.

Where This Comes From

The examples here cover Minnesota, New Hampshire and Iowa. Timing and local advice may differ elsewhere.

Common Questions

Are Leafcutting Bees Harmful to Roses?

Seldom. They are native, largely beneficial pollinators, and a healthy rose easily tolerates some lost leaf tissue.

Can Leafcutting Bees Kill a Rose Cane?

Unlikely. They sometimes nest in the largest canes but restrict tunneling to the pith and rarely girdle the cambium.

Do Leafcutting Bees Sting?

The evidence here does not address stinging.

Beetles clustered on rose blooms in the middle of a summer day are a familiar sight in much of the country. Japanese beetles feed on over 250 plant species, and roses rank among their favorites, so the rose bed is often where you spot them first. Knowing what they look like, when they arrive and how to respond keeps the damage in check.

Japanese Beetle: What You See

Start with the adult beetle itself, since it is the part you can catch in the act.

• Tufts of white hair show around the abdomen, just below the wing covers, and that is the sign that sets this beetle apart from similar ones.
• The beetles work on the topmost, youngest leaves first, whatever the height of the plant.
• In Georgia, they feed during the day and are most active from midmorning to early evening, so a midday check finds them where an evening check may not.
• Flowers and buds get eaten along with the foliage, and roses are among the plants they go for first.
• Adults usually turn up from late June through September in Indiana.
• In Indiana, the grubs live in the soil and measure 1/4 to 1 inch long, which is why they get mistaken for other white grubs.

Because the feeding starts at the top of the bush, a quick look at the newest growth tells you more than a glance at the lower canes.

Japanese Beetle or Something Else?

Several beetles visit roses, and a few grubs in the soil look much the same. A chewed leaf alone does not settle the question, so pair what you see with where and when you see it.

Looks like	How to tell them apart
Other beetles feeding on rose blooms and leaves	Look at the rear of the beetle for tufts of white hair at the end of the abdomen, and note whether it feeds in daylight.
May/June beetle and masked chafer grubs in the soil	In Indiana, the Japanese beetle grub is 1/4 to 1 inch long and resembles them, so the grub alone proves little. Adults with white tufts feeding on the bush above point to Japanese beetle.

If the grubs turn up in soil but you see no adults with white tufts on your plants, other beetles may be behind them. If you are unsure, have the specimen identified locally.

What Causes Japanese Beetle, and Where It Is Worst

The cycle starts in the ground. Adults lay their eggs in the soil, and the grubs overwinter deep down, then finish their growth the following spring. In Indiana, the adults emerge from the ground in mid-summer. Once emergence begins, a bed that looked clear can soon fill with beetles.

The timing shifts with the place. In South Carolina, adults begin emerging in mid-May and are present through August. In central Maryland, emergence begins in mid-June and peaks in early July, and the beetles stay active for about 4-6 weeks. In Wisconsin, they typically begin to emerge in late June and early July.

Your neighbors’ yards matter too, because adults can fly an average of 1 to 2 miles. This continuous migration means beetles keep arriving after you clear a bush. Japanese beetles are not established in California, so gardeners there are not dealing with them.

How to Treat Japanese Beetle

Treatment is mostly steady attention during the weeks when beetles are present, and it follows this order.

1. Check the bushes early in the season before damage appears, so that you catch the first beetles before they draw others in. Begin scouting at that stage.
2. Handpick beetles and drop them into soapy water, which removes them from the bush without any chemicals.
3. Clip off buds when beetles are abundant, since roses unfold too fast and are too attractive for sprays to protect the flowers fully.
4. Spray the bushes to protect the leaves, using only a product approved for roses and Japanese beetles in your area.
5. Repeat the spraying when beetles keep arriving. In Maryland, 2 or 3 spray applications may be needed to prevent serious injury to roses and grapes.
6. Let the bushes bloom again once beetles become scarce, so the plant can put its energy back into flowers.

Beetle bags from the store are not the answer, and beetles are hard to control once established, especially at population peaks. Community-wide programs that bring neighbors into integrated pest management can reduce their influence to a great extent.

How to Prevent Japanese Beetle Coming Back

Prevention follows the beetle’s calendar, from the soil in spring to the last adults of late summer.

• In Georgia, scout for adults and grubs from early spring.
• Before the first flight, which begins in mid-May in South Carolina, look over the bushes so that you find the first beetles quickly.
• When beetles are abundant in summer, clip the buds and protect the leaves instead of trying to save every flower.
• Once the beetles become scarce, let the bushes bloom again.
• Into late summer, keep checking, as adults can still be found through September in Indiana.
• Throughout the season, talk with neighbors about a shared plan, since the beetles move between yards.

Adult beetles seldom become a problem when a regular spray schedule already controls other insects.

Where This Comes From

The timing and treatment details here are specific to the states named in the text. Timing, spraying advice and approved products vary by state.

Common Questions

What Other Plants Do Japanese Beetles Eat?

Beyond roses, preferred hosts among garden plants include crape myrtle, zinnia, marigold, canna, evening primrose and dahlia. Grapes are a favorite too, and during population peaks the beetles can defoliate entire trees.

How Long Do Japanese Beetles Live?

In South Carolina, adults can live from 30 to 45 days. Since emergence stretches over weeks, new beetles keep replacing the old ones through the season.

Are Japanese Beetles a Problem in California?

Japanese beetles are not established in California. A beetle on a California rose is more likely something else, so check for white tufts at the end of the abdomen before treating.

Round holes in the petals of a white, yellow, apricot or pink rose usually point to hoplia beetle. The damage is easy to mistake for something worse, yet the beetle is small and the season for trouble is short. Knowing what the beetle looks like and when it flies makes the fix simple.

Hoplia Beetle: What You See

Look at the open flowers first, because that is where this beetle gives itself away.

• Neat, round holes appear in the petals of open flowers, mostly on white, yellow, apricot and pink roses.
• The adult is oval and about 1/4 inch long, small enough to hide among the petals.
• Its head and thorax are a dark, reddish brown, and the wing covers run from dark to light brown.
• Early buds can be chewed badly enough that the first flowers are destroyed.
• In California, the trouble shows up from late March to May and then stops.

If the holes appear in light-colored blooms and a small brown beetle is sitting inside the flower, you have your answer.

Hoplia Beetle or Something Else?

Not every chewed rose is a hoplia problem. A few other kinds of damage get blamed on this beetle, and a quick look at the leaves and the plant’s overall health sorts them out.

The beetle is a flower feeder, so damage that sits anywhere other than the blooms deserves a second look.

Looks like	How to tell them apart
Chewed leaves with holes or ragged edges	Hoplia beetle leaves the foliage alone, so leaf damage with untouched petals comes from another chewing insect.
Grubs in the soil near the rose, with a plant that looks weak	Hoplia grubs are crescent-shaped and live in soil, but they do not feed on rose roots, so a declining plant needs another explanation.
Holes only in dark-colored blooms	Hoplia adults go for light-colored flowers, so damage on dark roses alone with no beetles in the blooms points elsewhere.

When the damage sits on pale petals and the foliage looks clean, hoplia beetle is the likely cause. When the leaves are chewed too, look for a different pest.

What Causes Hoplia Beetle, and Where It Is Worst

The beetles live as grubs in the soil and fly into gardens as adults to feed on roses and other flowers. After feeding for several weeks, the adults fly back to their egg-laying sites. There is a single generation each year, which is why the problem arrives and leaves on a fairly fixed schedule.

Hoplia beetle is common in many parts of the state, especially the Central Valley. It is mostly a problem there from Sacramento south to Bakersfield. Adults are generally active from late March to early May, and damage is usually confined to a 2- to 4-week period in late spring.

Outside California, the beetle’s presence and flight period may differ.

How to Treat Hoplia Beetle

Hand removal is the practical response to beetles feeding on the flowers.

1. Check the open, light-colored blooms regularly during the flight season, so that you catch beetles before they have chewed through the petals.
2. Handpick the beetles off the flowers they are feeding on, so that each one is removed rather than driven to another bloom.
3. Shake the blooms gently over a bucket of soapy water, which drops hidden beetles straight into it.
4. Leave the beetles in the soapy water, so that they cannot climb out and return to the roses.
5. Skip any treatment of the leaves, since the beetles do not feed on them and the foliage is not where they are found.
6. Do not use a spray or other product unless it is approved for roses and this beetle in your state.

In California, damage is usually confined to a 2- to 4-week period in late spring, so the routine does not run long. Once the adults have fed and flown back to their egg-laying sites, the roses are left in peace until the next year.

How to Prevent Hoplia Beetle Coming Back

Hoplia beetle cannot be kept away for good, but a gardener who knows the calendar is rarely caught off guard.

• Before the season opens, plan to watch your white, yellow, apricot and pink roses most closely, since those are the blooms the adults prefer.
• As the first buds swell, begin looking inside them and the newly opened flowers, because early buds are the ones the chewing can destroy.
• Through the weeks when adults are flying, keep removing beetles from the flowers so that fewer feed and fewer return to lay eggs.
• After the adults have gone, stop the daily checks and leave the foliage alone, since this beetle does not feed on leaves.

In affected California gardens, repeat the checks and handpicking during the flight season.

Where This Comes From

The details here describe California gardens. Timing and approved products vary by state, so do not apply California dates elsewhere.

Common Questions

Do Hoplia Grubs Eat Rose Roots?

No. The larvae are small, crescent-shaped grubs that live in the soil and feed on roots, but they do not feed on the roots of rose plants.

Do Hoplia Beetles Feed on Flowers Other than Roses?

Yes. The adults fly to gardens where they feed on roses and other flowers.

Is Hoplia Beetle a Problem Outside California?

Hoplia beetle is common in many parts of California. Outside California, its local presence and active period may differ.

Rose leaves with ragged, scalloped edges and no insect in sight usually mean something is feeding after dark. The likely culprit is the fuller rose beetle, a flightless weevil that chews leaves, buds and flowers at night and, in California, is known to hide by day. Knowing its look and its habits makes it much easier to confirm.

Fuller Rose Beetle: What You See

Start with the faint white band along each side of its wing covers.

• A faint white band runs along each side of the body, on the wing covers.
• The body is light brown to ash-gray, with a short snout and elbowed antennae that spring from it.
• Adults measure about 3/8 inch long, small enough to vanish among the leaves.
• Leaf edges look notched, serrated and ragged, and flowers get chewed too.
• During the day the adults sit on the undersides of leaves, and they cannot fly (a habit noted in California).
• In North Carolina, adults first appear in July and keep emerging through November.

A flashlight after dark, aimed at the leaf edges, can help you catch one at work.

Fuller Rose Beetle or Something Else?

Ragged leaves can come from many chewing pests, and stunted growth has many causes, so one clue is never enough. Pair what you see on the plant with when and where you see it.

The pairs below separate this weevil from the usual look-alikes.

Looks like	How to tell them apart
Another chewing insect, with notched leaf edges	A fuller rose beetle feeds at night; in California, adults often hide on leaf undersides during the day.
A rose that grows poorly and looks short of water or nutrients	Damaged roots cause that stunting, so check the leaf margins for notches too. If they are clean and the beating test below turns up nothing, the symptoms may have another cause.

Notched edges together with weevils that drop from the canes when you shake them point to this beetle. Clean leaves and no weevils point elsewhere.

What Causes Fuller Rose Beetle, and Where It Is Worst

The adults emerge from the soil and crawl up the rose to feed, since they cannot fly. Males of this species have never been found. Eggs are laid in groups, in protected plant parts or in or on the soil.

The host list is very long. Citrus, strawberry, beans, peach, rhubarb and potato are all on it, along with azalea, begonia, gardenia and hibiscus. A rose growing near any of these can be visited by the same weevils.

Timing depends on where you garden. In North Carolina, most beetles overwinter as larvae in the soil, then pupate in spring near the surface. Adults appear from July onward. Fuller rose beetles feed on roses and many other host plants.

How to Treat Fuller Rose Beetle

Work in the order below, starting with confirmation and ending with local advice on what is approved for your state.

1. Check the undersides of leaves by day to look for hiding adults.
2. Go out after dark with a flashlight, because feeding happens at night and the weevils are easiest to catch in the act.
3. Beat the shrub over a light sheet or tray and collect the adults as they drop, which shows you whether weevils are present at all.
4. Watch for fresh leaf damage or set ground traps, since both tell you when adults are emerging in your yard.
5. Water through dry spells, because roots damaged by larvae cannot take up water well, and in Florida severely damaged plants have died in drought.
6. Contact your state’s extension service before using any spray, so that you get only what is registered where you live.

Keep your expectations modest. Most of what you see is leaf damage, and a bush that is otherwise growing steadily can carry some notched edges.

How to Prevent Fuller Rose Beetle Coming Back

Because the cycle runs from soil larvae to leaf-feeding adults, prevention is mostly about watching at the right moments.

• In North Carolina, larvae pupate near the soil surface in spring, and adults first appear in July.
• Look under the leaves by day for adults hiding there.
• From July through November in North Carolina, shake the canes over a tray once in a while, since adults keep emerging through the fall.
• Severely damaged roots can leave the plant vulnerable during drought.

Repeat the same night walk when fresh leaf damage appears.

Where This Comes From

The facts here come from university extension and government pages written for places such as North Carolina, Florida and California.

Timing and local advice change from state to state, so confirm dates and approved treatments with your own state’s extension service.

Common Questions

Do Fuller Rose Beetles Kill Roses?

Rarely. The weevils do little serious harm beyond how the plant looks. Under a heavy attack, adults can eat the whole leaf except the midrib. The dangerous case is a root system damaged badly enough that the plant dies in drought or picks up a fungal infection, as reported in Florida.

Are the Larvae in the Soil a Problem for Roses?

Not usually. The larvae are root feeders, but they do not seriously damage roses. Poor, stunted growth is the sign that root damage has become heavy.

What Else Does This Weevil Feed On?

Many plants. Citrus, strawberry, beans, peach, rhubarb and potato are among the main hosts. Apple, azalea, begonia, blackberry, gardenia, hibiscus, lily, raspberry and others also get chewed.

Ragged leaves with see-through patches usually point to small larvae feeding on the underside, and most of them are not true caterpillars at all. They are sawfly larvae, and they behave differently from moth and butterfly caterpillars. Knowing which one you have decides whether you pick, prune or simply tolerate the damage.

Caterpillars on Roses: What You See

The larvae that most often get called caterpillars on roses are small, tapered and slimy, and they are easiest to spot by the damage they leave on the leaves.

• Leaves show windowpane damage, small papery patches that are nearly see-through, because the larvae eat the soft tissue and leave the veins.
• The larvae sit on the underside of the leaf, where they look like tiny caterpillars with a bead-like head and jointed legs.
• Their shape is tapered and their skin looks slimy, which gives them a vague resemblance to a true slug.
• Full-grown larvae reach up to ¾ inches in length, and older ones chew entirely through the leaf instead of leaving a thin layer.
• Heavily fed-on leaves turn brown, curl and dry out, and in Kentucky the first damage shows up in April.

In Wisconsin the damage typically starts in early to mid-May and can run through mid-June.

Caterpillars on Roses or Something Else?

Several different insects chew rose foliage, and the fix depends on which one you have. Sawfly larvae are related to wasps, so they are not caterpillars even though they look like them.

Real caterpillars, the young of moths and butterflies, turn up on roses only infrequently, so check the clues below before assuming.

Looks like	How to tell them apart
Roseslug sawfly larva	Slimy, tapered body with a bead-like head, found on the leaf underside, leaving windowpane patches with the veins intact.
Leafroller or tent caterpillar	Leaves tied or rolled together with silk, and a caterpillar or its frass hiding inside when you open the roll (seen in California).
Budworm caterpillar	Flower buds bored into, with the caterpillar or its frass found inside the bud.

Other caterpillars reported on roses in South Carolina include the corn earworm, stinging rose caterpillar and puss caterpillar, so wear gloves when handling any hairy one. Their feeding leaves holes or irregular areas in the leaf blade instead of windowpanes.

What Causes Caterpillars on Roses, and Where It Is Worst

The cause is an insect that specializes in roses. Female roseslug sawflies are shiny black with yellowish-orange markings. The roseslug sawfly is native to Europe and now feeds on wild and cultivated roses alike.

No soil type or climate zone is singled out, so any rose can be visited. Timing differs by place: damage starts in April in Kentucky and in May and June in Wisconsin, with northern Wisconsin running slightly later.

The kinds of sawfly differ too. In California the bristly roseslug is the most common, and it occurs mainly in cooler areas such as near the coast. The curled roseslug and the roseslug are occasional pests there, and at least three sawfly species attack roses in California.

How to Treat Caterpillars on Roses

The damage from rose slugs is mostly cosmetic, so a calm, hands-on approach is usually enough. Work in this order.

1. Turn the leaves over and look on the underside, so that you find the larvae where they actually feed.
2. Hand pick the larvae you find, which removes them before they grow large enough to chew right through the leaf.
3. Prune out infested buds and rolled leaves, since they often hide caterpillars inside, and look for the caterpillar or its frass to confirm.
4. Dispose of the clippings promptly in a sealed bag, so that nothing crawls back onto the plant.
5. Check the plant regularly because new damage can keep appearing throughout the growing season.
6. Contact your state extension service before reaching for any spray, so that you learn what is approved where you live.

Leaves that are already brown and dry will not recover.

How to Prevent Caterpillars on Roses Coming Back

Prevention comes down to timing your checks to the season, since the larvae follow a predictable calendar.

• In Kentucky, start inspecting leaf undersides in April, when roseslug damage first appears.
• In Wisconsin, look closely from early to mid-May through mid-June, or slightly later in northern parts of the state.
• Keep checking regularly, and remove any rolled leaves or damaged buds as soon as you see them.

A short look at the plant can catch feeding damage early.

Where This Comes From

The details here come from university extension guidance written for Kentucky, Wisconsin, South Carolina and California. Rules and timing vary by place, so confirm what applies to you with your state’s extension service.

Common Questions

Do Rose Slugs Kill Roses?

Rarely. Rose slugs and sawflies generally cause mostly cosmetic damage, though heavy infestations can turn leaves brown and curl them.

Can Rose Slugs Spread to Other Plants?

They specialize in roses, but there are reports of them damaging strawberries and raspberries as well.

Why Are the Leaves Turning Brown with See-Through Spots?

Windowpane patches on the leaf, together with larvae on the underside, point to sawfly feeding. The thin areas eventually brown and dry.