If you've spotted a group of long, soft-looking beetles chewing on your tomato plants, potatoes or garden flowers, take a closer look before you reach for them. They may be blister beetles. Around your Ridgewood home, these beetles can turn up in vegetable gardens and flower beds in summer, often feeding together in clusters. The name says a lot. Blister beetles carry a chemical that can raise blisters on skin if you crush or handle one. Below, we'll cover how to identify blister beetles, what they eat, why they matter and how to deal with them safely. If you're not sure what's in your garden, our pest inspection services can help you identify it.
What Blister Beetles Are
Blister beetles are a family of beetles found across much of North America. Several kinds live in the Northeast. They share a few features that set them apart from other beetles:
- Shape. Long and slender, with a soft body.
- Narrow neck. The section behind the head is narrower than the head itself, so they look like they have a distinct neck.
- Soft wing covers. The wing covers are flexible and leathery rather than hard and shiny.
- Color. Varies by species. Some are solid black or gray. Others have yellow or orange stripes, or black wing covers edged in gray.
Adults feed on leaves and flowers. Many species gather in large groups, which can strip a plant quickly. The larvae have a very different life. Some feed on grasshopper eggs in the soil, and others live in the nests of ground-nesting bees.
Why They Show Up
Blister beetles are most active in summer. They're drawn to plants they like to eat, including:
- Tomatoes, potatoes, eggplant and peppers.
- Beans, beets and leafy greens.
- Flowers such as asters, goldenrod and other late-summer blooms.
- Alfalfa and clover.
Years with lots of grasshoppers can be followed by more blister beetles, since some larvae depend on grasshopper eggs for food. Adults can also move in suddenly. A garden that looked fine one day may have a cluster of beetles on a single plant the next. They often feed in one spot until the plant is stripped, then move on together. Because they're attracted to flowers, they can show up in ornamental beds as well as vegetable gardens, often in late summer when many plants are blooming.
Are Blister Beetles Dangerous?
Blister beetles don't bite or sting, and they don't come indoors to breed. The concern is a chemical in their bodies called cantharidin.
- Skin contact. If a beetle is crushed or pressed against your skin, cantharidin can cause a blister, usually a few hours later. Avoid touching your eyes or face after handling plants where they're feeding. If you get a blister that's large, painful or near the eyes, or if you're worried about it, see a doctor.
- Animals. Cantharidin is toxic to animals that eat the beetles. Horses are known to be at risk when beetles end up in hay. If you think a pet or animal has eaten blister beetles, call your veterinarian right away.
Blister beetles aren't the only beetles that feed on vegetable plants. If you're seeing yellow and black striped beetles on squash or cucumbers, our guide on how to control cucumber beetles can help you tell the difference.
How To Tell Them From Lookalikes
Soldier beetles and some leaf beetles can look similar at a glance. Soldier beetles are also slender with soft wing covers, but they don't have the narrow neck, and they're often orange with black spots. Cucumber beetles are smaller, harder and more compact. When in doubt, don't touch. Take a photo and compare, or ask for help with identification.
How To Deal With Blister Beetles Safely
- Wear gloves. Always wear gloves when working around plants where they're feeding.
- Knock them into soapy water. Hold a bucket of soapy water under the plant and brush or shake beetles into it with a stick or gloved hand.
- Don't crush them. Crushing releases cantharidin onto your skin and tools.
- Use row covers. Lightweight fabric over vulnerable crops keeps adults off.
- Check plants often. Groups can arrive suddenly, so look over the garden every few days in summer.
- Wash up. Wash hands and any exposed skin with soap and water after gardening.
- Keep pets away. Don't let pets chew on beetles or plants where they're feeding.
When To Call A Professional
For crop-specific advice, a garden center or your county office of Rutgers Cooperative Extension is a good resource. EcoFusion doesn't provide vegetable garden treatments, but we can help when you aren't sure what you're dealing with or when insects from the yard are making their way into your home. Our NJ DEP-licensed technicians can inspect your property, identify the insects you're finding and recommend a plan using Integrated Pest Management and EPA-registered, eco-safe products.
Blister beetles are a garden pest worth handling with care. Gloves, a bucket of soapy water and regular checks can protect both your plants and your skin at your Ridgewood home.