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Blister Beetles

Blister Beetles

Family Meloidae

Insectalso: Blister beetle

Slender, soft-bodied beetles that can descend on a garden in swarms and defoliate plants fast, then vanish. Blister beetles chew leaves and flowers of tomatoes, beans, potatoes, and many other plants, and they carry an irritating chemical, cantharidin, that can blister skin, so they are handled with care.

🔎 How to spot it

Look for elongated, narrow beetles, half an inch to an inch long, with a distinct narrow neck behind the head and soft, flexible wing covers. They come in solid black or gray or in stripes of yellow or orange and black. They often appear suddenly in groups, clustered on and defoliating a few plants, especially flowers and tender foliage, then move on.

🥀 Damage it causes

Blister beetles chew leaves, flowers, and sometimes fruit, and a swarm can defoliate plants quickly, hitting tomatoes, potatoes, beans, beets, chard, and many flowers. They tend to feed in groups along field edges, so damage is often patchy and concentrated. Their numbers and damage can build fast and then disappear as the beetles move on.

🛡️ Prevent it

Scout regularly during summer, especially edges and flowering plants, so you catch a group before it spreads. Floating row cover keeps them off vulnerable plants. Their larvae are actually beneficial, feeding on grasshopper eggs in the soil, so blister beetle outbreaks often follow grasshopper years; managing grasshoppers indirectly limits them.

🧯 If it is already here

Handpick into soapy water, but wear gloves, because crushed beetles release cantharidin that can blister skin. Knock them from plants into a bucket of soapy water in the cool of morning when they are sluggish. For heavy infestations, labeled insecticides give control, but spot-treat the affected plants rather than blanket-spraying, to spare pollinators and the beneficial larval stage.

💡 Good to know

Take the blistering warning seriously: do not crush blister beetles against bare skin, since their cantharidin can raise a welt, and the same toxin makes them dangerous to horses if baled into hay. Because their larvae eat grasshopper eggs, the beetles tend to surge in the years after big grasshopper populations.

🌱 Plants it attacks

318 plants in the library can be attacked by this pest

Adirondack Blue PotatoAdzuki BeanAfrican MarigoldAgapanthusAgeratumAji Amarillo PepperAlice du Pont Mandevilla🥔All Blue PotatoAmethyst Falls WisteriaAmish Paste TomatoAnaheim PepperAnemoneAngelique TulipAngeloniaAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApril Tryst CamelliaArizona Sun Blanket FlowerArugulaAugust Beauty GardeniaAutumn Joy SedumBachelor's ButtonBanana PepperBarbara Karst BougainvilleaBeauregard Sweet PotatoBecky Shasta DaisyBee Balm🍅Beefmaster TomatoBenarys Giant ZinniaBengal Tiger CannaBetter Boy Tomato🥬Bibb Lettuce🍅Big Beef TomatoBig Boy TomatoBlack BeanBlack Beauty EggplantBlack Cherry TomatoBlack Krim Tomato🥬Black Seeded Simpson LettuceBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBloomsdale SpinachBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBlue Lake Green Bean🍅Box Car Willie TomatoBrandywine TomatoBroad Windsor Fava BeanBrunneraBull's Blood BeetBurning BushButtercrunch LettuceButterfly Blue Pincushion FlowerButterfly Marguerite DaisyButterfly WeedCafe au Lait DahliaCaladiumCalendulaCalibrachoaCalifornia Giant ZinniaCalifornia PoppyCampanulaCannellini BeanCardinal FlowerCarolina GeraniumCarolina JessamineCarolina Reaper PepperCayenne PepperCelebrity TomatoCherokee Purple TomatoChicoryChioggia BeetClimbing HydrangeaClimbing Prairie RoseCocktail Vodka BegoniaColeusCollard GreensCoral Drift Groundcover RoseCosmosCranberry BeanCreeping PhloxCubanelle PepperCupani Sweet PeaCylindra BeetDandelionDavid Garden PhloxDelft Blue HyacinthDenim n Lace Russian SageDetroit Dark Red BeetDusty MillerDutch Master DaffodilEarly Girl TomatoEastern Red ColumbineEdamameEndiveEndless Summer HydrangeaEnglish Lavender

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.