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Sawflies

Sawflies

Suborder Symphyta

Insectalso: Roseslug, Pearslug, Pear slug

Caterpillar-like larvae of small wasp relatives that skeletonize the leaves of roses, pears, cherries, and other plants, leaving a lacy, windowpane look. The rose slug and pear slug are common garden sawflies; despite the slug nickname they are not slugs at all, and a strong jet of water or a soap spray knocks them out.

🔎 How to spot it

The larvae look like small caterpillars, pale green to yellow-green, up to about three quarters of an inch, and some, like the pear slug, are coated in shiny olive-green slime that makes them look like tiny slugs. The damage is the giveaway: they graze the soft tissue between the veins, leaving the veins and a thin translucent layer behind, so leaves look skeletonized, lacy, or windowpaned and later brown.

🥀 Damage it causes

Sawfly larvae skeletonize leaves, grazing one surface and leaving the veins, which turns the foliage lacy and brown and, in a heavy case, can defoliate roses and the leaves of pear, cherry, and other ornamentals and fruit trees. The damage is mostly cosmetic on established plants but can be unsightly and weaken young or heavily infested ones.

🛡️ Prevent it

Scout roses and host trees in late spring and early summer when the larvae first appear, since catching them early keeps damage light. Encourage natural enemies and avoid broad-spectrum insecticides that kill them. There is usually just one generation a year on roses, so getting through the spring flush is often enough.

🧯 If it is already here

A strong jet of water knocks the soft-bodied larvae off the leaves, and because their bodies are so delicate most do not survive the fall; this alone controls light infestations. Handpick where practical. For heavier infestations, insecticidal soap, neem oil, or spinosad aimed at the larvae works well. Note that Bacillus thuringiensis (Bt) does not work on sawflies, since they are not true caterpillars.

💡 Good to know

Sawflies are wasp relatives, not moths or butterflies, which is why Bt, the go-to spray for caterpillars, has no effect on them, an important distinction when choosing a control. The slug-like roseslug and pearslug are the larvae, not actual slugs, and a simple blast of water is often all the control a garden needs.

🌱 Plants it attacks

192 plants in the library can be attacked by this pest

African Blue Basil🍓Albion StrawberryAmerican Beauty Dragon FruitAnjou PearAroniaArugulaAsian PearAunt Molly's Ground CherryAutumn Joy SedumBalsam FirBartlett PearBeach PlumBengal Tiger Canna🥬Bibb LettuceBilberryBing CherryBlack CrowberryBlack CurrantBlack Raspberry🥬Black Seeded Simpson LettuceBlack Tartarian CherryBloomsdale SpinachBlue Bird DelphiniumBluecrop BlueberryBocking 14 ComfreyBok ChoyBosc PearBoysenberryBraeburn AppleBrunneraBurdockButtercrunch LettuceCafe au Lait DahliaCaladiumCalifornia PoppyCampanulaCarawayCardinal FlowerCardoonCeleriacCeltuceChampagne LoquatChervilChicoryChokecherryCinnamon BasilClimbing Prairie RoseContender PeachCoral Drift Groundcover RoseCornelian CherryCortland AppleCosmic Crisp AppleCranberryCrimson Cherry RhubarbCulantroCupani Sweet PeaDamson PlumDutch Master DaffodilEastern White PineElberta PeachElderberryEndiveEvergreen HuckleberryFantasia NectarineField PeaFlorence FennelFrench MarigoldFriséeFuji AppleGala AppleGarden PrimroseGarland ChrysanthemumGenovese BasilGoji BerryGooseberryGraham Thomas English RoseGranny Smith AppleGrape HyacinthGreek BasilGreen Globe ArtichokeGreen Leaf LettuceHansa Rugosa RoseHawthornHeritage RaspberryHollyhockHoly BasilHoneoye StrawberryHoneyberryHoneycrisp AppleHusker Red PenstemonIceberg Floribunda RoseIceberg LettuceIndian HawthornItalian Large Leaf BasilJackmanii ClematisJersey Knight AsparagusJune-Bearing StrawberryJuniperKarma Choc DahliaKnock Out Rose

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.