A rosebud that swells, colors up, and then refuses to open is the classic sign that thrips have been feeding inside it. These slender insects work out of sight in the folds of the petals, which is why the damage often shows up before the pest does. The good news is that the harm is mostly to looks.

Thrips: What You See

Thrips are hard to catch in the act, so you read the bloom and the bud for clues, starting with the one that gives them away.

• A bud that stays closed and never opens is the sign gardeners notice first, and heavily infested buds in particular may fail to open.
• The outer petals carry brown edges, and the petal itself is often malformed, because the insect chews and sucks the juices.
• Brown spots dot the petals of flowers that do open, and they show up best on lighter colored blooms.
• Tiny brownish-yellow insects with fringed, feathery wings sit at the base of the petals, at less than 1/16 inch long.
• Leaves can look distorted too, since thrips also feed in leaf buds.

In North Carolina, roses are most susceptible in June, so that is when to look closely.

Thrips or Something Else?

Petal browning and stalled buds have other causes, so a single clue is not enough to name thrips. Pair what you see with where it is happening, and add a quick test before you reach for any treatment.

Peel back the outer layer of petals on a healthy blossom and look at the base. Blowing lightly into a bloom makes thrips move, which makes them easier to spot.

Looks like	How to tell them apart
Browned petal edges from a stressed or damaged bloom	No tiny insects appear at the petal base when you peel back the first layer, and a light puff of breath produces no insect movement.
Distorted new leaves from sap feeders such as aphids	Aphids cluster visibly on tips and buds, while thrips hide inside the bud and the petal base.

Unopened buds can also come from weather or watering stress, so check inside the bud for the narrow, fast-moving insects before you decide.

What Causes Thrips, and Where It Is Worst

Thrips are tiny flying insects, and the wind carries them into your garden on warm, sunny days. They arrive on their own, so a clean yard can still get them. Roses are one of several hosts, along with strawberries, bell pepper, and white clover.

Warm weather speeds them up. In North Carolina they reproduce through the year, with most of their 12 to 15 generations falling in the warmer months, and in summer the adult stage arrives in about 11 days. Populations can build quickly once the weather turns warm.

Other species feed on roses too. Chilli thrips are a nuisance to rose growers because their feeding damages both foliage and flowers. Various thrips species feed on roses, so do not rule them out without checking the buds.

How to Treat Thrips

Because the damage is cosmetic and will not harm the bush, start with the gentlest steps and decide how far to go based on what you see.

1. Check a few buds as they start to form, so that you catch thrips before the blooms are ruined.
2. Pick one healthy blossom and peel back the first layer of petals, looking at the base for tiny brown-to-orange insects.
3. If thrips are present, decide whether the cosmetic damage warrants treatment.
4. Leave beneficial insects alone, since some gardeners report thrips are eaten by the same insects that consume aphids.
5. Decide whether a spray is worth it for you, because in Arizona gardeners growing show-quality blooms may spray buds before they open with an insecticide labeled for thrips on roses.

If you consider spraying, check which products are approved for roses where you live. Buying predatory mites is not a reliable fix, since they typically do not establish well on roses. Smooth rose leaves lack the protective structures underneath that the mites need for shelter. Interestingly, when pepper plants were added as a home for the mites, thrips damage to the roses decreased significantly.

How to Prevent Thrips Coming Back

Thrips arrive by wind, so you cannot keep them out, but timing your checks and cleanup shrinks the damage.

• As flower buds begin to form, start looking inside a few of them regularly, because that is when thrips move in.
• Keep checking buds through the warmer months, when most thrips generations occur.
• In June in North Carolina, when roses are most susceptible, check lighter colored blooms first because browning shows there.

Where This Comes From

Local timing and approved treatments vary.

Common Questions

Will Thrips Kill a Rose Bush?

No. The damage is cosmetic and will not harm the bush, though it can spoil the look of the blooms.

Why Do Rosebuds Turn Brown and Not Open?

Thrips chewing and sucking the petals cause brown edges and malformed petals, and heavily infested buds may fail to open. Check inside the bud for tiny insects to confirm.

How Big Are Thrips on Roses?

They measure less than 1/16 inch and are barely visible without a magnifying glass. Blowing lightly into a bloom makes them move so you can spot them.

Rose leaves that turn gray or speckled in hot, dry weather, often with fine webbing underneath, usually point to spider mites. These pests feed on the underside of the leaf, so the damage shows from above before the culprit is easy to find. Washing the plant is a useful first move, and regular watering helps keep the rose from becoming drought-stressed.

Spider Mites: What You See

The first sign is on the leaf surface, and the mites themselves are harder to spot.

• Tiny pale spots crowd together on the leaf, a pattern called stippling, and the leaf can look gray or finely speckled.
• Webbing appears on the underside of the foliage, though some species produce none.
• Lower leaves turn a fuzzy yellow with red specks, and those specks are the mites.
• Each mite is about the size of the period at the end of this sentence, so a magnifier helps.
• In California, mites usually appear first on the undersides of leaves and may move to the upper surfaces as their numbers grow.
• Shaken over a sheet of white paper, the leaves drop mites that can be seen scurrying around.

In Arizona, hot and dry weather from May through September is the time to look.

Spider Mites or Something Else?

Speckled, off-color leaves have more than one cause, and a speck on the leaf is not enough to name the culprit. Check where the speckling sits and whether anything moves when you shake a leaf over white paper.

Southern red mites are the closest lookalike on roses, and they follow a different seasonal pattern.

Looks like	How to tell them apart
Southern red mites, with the same speckled leaves	In South Carolina, southern red mite numbers climb in cool spring and fall weather and drop in summer, while two-spotted spider mites build in hot, dry spells.

Powdery mildew is a disease, not a mite. It also troubles roses, especially in greenhouses, but nothing scurries across the paper when you shake a mildewed leaf.

What Causes Spider Mites, and Where It Is Worst

Mites settle where conditions suit them. Dry, dusty air favors them, and females lay more eggs and develop faster at lower relative humidity. A rose that is short of water is more susceptible, which is why a dry summer spell hits so hard.

Warmth speeds the whole cycle. Development from egg to adult shortens as temperatures climb:

• At 54F, it takes 40 days.
• At 70F, it drops to 14 days.
• At 86F, it is only 7 days.

Hot, dry weather is the usual trigger. In Arizona the watch runs from May through September, and in South Carolina two-spotted spider mites flare in hot, dry spells while southern red mites take over in cool spring and fall weather. Roses are among their favored hosts, and a low-level mite population may do no harm.

How to Treat Spider Mites

Confirm the mites first, then start with water, which is the gentlest tool you have.

1. Shake leaves over white paper, so that you know you are dealing with moving mites and not another leaf problem.
2. Decide whether to treat at all, since a low-level population may not harm the rose.
3. Wash the plant with a strong stream of water, aiming at the undersides of the leaves, because that is where the mites feed.
4. Try soapy water if plain water does not do enough, since in Arizona it may be more effective.
5. Repeat the washing regularly, because mites that survive keep laying eggs and the numbers rebound.
6. If washing is not enough, get local advice about treatments registered where you live.

Watch how the numbers behave after any treatment. In North Carolina trials, a high kill that declined within 2 or 3 weeks pointed to surviving mites or eggs, while a high kill soon after treatment meant all stages were hit.

How to Prevent Spider Mites Coming Back

Prevention follows the season, because mites build with heat and dryness and a roughly timed routine keeps them in check.

• Look at the undersides of the lower leaves, where mites usually show up first.
• Before the hot, dry stretch, water the roses well to reduce drought stress.
• Through the hot months (May through September in Arizona), rinse the foliage regularly, which also washes off the dust mites favor.
• In cool spring and fall weather in South Carolina, keep checking, since southern red mites peak then.

Regular checks catch a problem while it can still be washed away.

Where This Comes From

Some timing and treatment details apply only in the states named above. Timing and treatment rules vary by place, so seek local advice before acting.

Common Questions

Can Spider Mites Harm a Rose?

They can. Mites suck the contents of leaf cells and remove chloroplasts, which weakens the leaf’s ability to turn sunlight into food. Heavy feeding can dry leaves up and drop them, as reported in California.

Do Spider Mites Always Leave Webbing?

No. Some species produce webbing and others do not, so a rose can be infested without any silk. Stippling and the white-paper shake test are steadier signs.

What Other Plants Do Spider Mites Favor?

Roses share the list with bee balm, butterfly bush, catmint, dahlia, marigolds, Russian sage, verbena and New Guinea impatiens. Mites are less common on woody trees and shrubs than on semi-woody shrubs like roses, so plants beside your roses are worth a look.

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.