How To Get Rid Of Blister Beetles


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Wondering how to get rid of blister beetles in your garden?

Blister beetles are a nasty, toxic pest in your garden that can cause skin irritation. The best ways to control them naturally is diatomaceous earth, handpicking, and trap crops.

But learning more about this common garden pest will help you recognize it from other similar beetles and know when the best times are to start looking for it in your garden.

This can make all the difference when you are trying to control a pest in your garden.

Early control can help save your plants from damage and mean the difference between losing your garden or having a great harvest.

How To Get Rid Of Blister Beetles text overlaid on a photo of a black blister beetle with a red head on a leaf.

Identification

Blister beetles are normally found on flower plants and although there are many types and they come in many colors and patterns they can easily be identified.

Unlike most beetles the blister beetle has a narrower thorax then it’s head or abdomen. It’s back is covered by soft leathery wings.

Do Blister Beetles Bite?

Black blister beetle with a red head on a leaf.
Black blister beetle with a red head.

Blister beetles don’t have singers and their jaws are not strong enough to break through human skin.

However, blister beetles contain the chemical cantharidin in their body fluids. This is their natural defense against predators.

When the beetle feels threatened it squeezes this fluid out from their leg joints. It’s this liquid that can cause skin blistering and burning feelings on animals and people.

This is why it’s a very bad idea to kill, crush, or handle blister beetles with your bare hands.

Although cantharidin is very toxic to its predators, it is not toxic to human skin. It will however cause painful blisters or welts on your skin after touching or crushing a beetle.

Blister beetles killed during the process of making hay can also cause blistering to the mouths of livestock.

Accidental ingestion of these beetles or their fluids can be fatal to livestock. If you suspect that your animal has eaten blister beetles you should contact your veterinarian.

Lifecycle

Black and orange blister beetle.
Black and orange blister beetle.

Blister beetles are found throughout Canada and the United States. In most areas, the beetle will produce one to two generations each year.

Larva from the second generation overwinters in the soil during their 6th instar (growth stage) becoming active when the soil warms up in the spring.

Adult beetles are often found in gardens, meadows, and hay fields from June to September with their peak being in July.

After breeding the females lay 4 to 6 egg clusters each containing 50 to 300 eggs in the soil. It takes 10 to 24 days for the larva to hatch.

Soon after they seek out prey to feed on. Blister beetle larva eats a lot of grasshopper eggs but since they also do a lot of other damage it’s best to find other ways to prevent grasshoppers.

The beetle larva will often also wait in flowers and attach itself to bees. Once back at the beehive it feeds on the bee larva.

Damage

Brown blister beetle on a flower.
Brown blister beetle on a flower.

Adult blister beetles feed on the leaves near the top of plants. They are also attracted to flowers and like to drink the nectar and eat the pollen.

This can cause a lot of damage to plants because it stops the plant from being able to produce fruit when the flowers are eaten.

They most commonly feed on vegetables like tomatoes, potatoes, eggplant, and melons. But also damage field crops like soybean, sweet clover, cotton, and alfalfa.

Control

Orange blister beetle with black spots.
Orange blister beetle with black spots.

Diatomaceous Earth (DE)

One effective way of killing blister beetles in your garden is to use diatomaceous earth.

Sprinkling this organic powder over and around your plants helps to get rid of the current problem and prevent new beetles from moving in.

You can get diatomaceous earth here.

Handpicking

Handpicking is another good way to control the beetles in your garden. But make sure to wear gloves to protect yourself from their toxin.

Using a stick brush them off the plant and into a can of soapy water where they will drown.

Blister beetles that are knocked off the plant and land on the grown will often play dead. But don’t fall for this as they will quickly find there way back onto the plants to continue feeding.

Their “playing possum” when disturbed does make it really easy to collect them off the ground to dispose of though.

Trap Crop

Another way you can use to prevent blister beetle damage in your garden is to plant a trap crop away from your main garden.

One of their favorite foods is pigweed, a common weed in our area.

Planting a patch in a remote corner of your garden may lour them there where you can deal with them all in one place.

On the other hand, if pigweed is common on weed throughout your garden, eliminating this plant could help reduce the number of beetles attracted to your vegetable patch.

Active Time
20 minutes

Total Time
20 minutes

Difficulty
Easy

Instructions

  1. Use diatomaceous earth sprinkled over and around your plants to kill blister beetles that are already feeding on your plants. Apply the powder as needed to help control them.
  2. Handpicking is another simple method of controlling this pest. Make sure to wear good gloves to protect your skin in case you touch them directly. Then using a stick knock the beetles into a can of soapy water.
  3. Plant a trap crop in a far corner of your garden. They love the pigweed plant and will often leave your other plants to feed on it. This makes it easier to find and remove blister beetles.

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