How to Control Blister Beetles. Blister beetles are leaf-feeding insects. Also known as oil beetles, they're members of the Meloidae family. Blister beetles give off a chemical called cantharidin, a toxin that affects both animals and people. The toxic properties of cantharidin are used by veterinarians as a counterirritant and blistering agent.

Step 1

Pick blister beetles off the plants with your hands. Wear gloves to protect your hands, as blister beetles discharge a caustic fluid that can harm your skin.

Step 2

Leave wide rows between plantings or clear out the surrounding weeds, grass and plants. Blister beetles will not cross wide rows, and they do not like to enter empty spaces.

Step 3

Keep blister beetles away with horseradish. Put the horseradish root in water and use it as a spray.

Step 4

Brush the blister beetles into pans of kerosene or kill them with systemic poisons or contact insecticides.

Step 5

Dust your infected plants with equal parts of lime and flour. Do this at the warmest time of the day.

Step 6

Harvest your crops before bloom. Blister beetles live in swarms or colonies, and they feed on many types of blossoms and foliage. This includes field crops such as vegetables, vines, trees and flowers.

Step 7

Use a registered insecticide before you harvest if blister beetles are present. Visit a site like (see Resources below) to see what the insects look like.