Beware of the Blister Beetle

Blister beetles are a common pest found swarming in crop fields and gardens. The secretion they release when injured or killed contains a toxin known as cantharidin, which can severely injure animals and humans when ingested. 

Cantharidin is a substance that has been used to burn off warts and interestingly enough, an aphrodisiac throughout history, but is poisonous in large doses. 

Cantharidin can cause severe damage and even be lethal if swallowed. Animal livestock is susceptible to accidentally swallowing the toxin because of dead beetles infested in bales of hay. 

A young child who may accidentally swallow the toxic beetle can get severe urinary tract and gastrointestinal lining damage from it. 

Not only do these notorious beetles threaten humans and animals, but they are also a danger to gardens, landscapes, and farms, feeding on leaves, plant blossoms, flowers, and hay. 

Learning how to Identify the blister beetle is extremely important since it tends to resemble the asparagus beetle with more than 200 types of the toxic pest in the U.S alone. 

Although the adult beetle varies in color, most grow to an inch in length and have long soft bodies with wide heads and antennas that are as long as their body. 

Depending on the species, their colors can be bright, striped, or dull. Some can be grey and brown with yellow stripes while others like the black blister beetle are completely black. 

Adult blister beetles lay their eggs in late spring. The female beetle lays hundreds of eggs in a cluster just barely below the surface of the soil.

The eggs hatch in less than two weeks and white larvae emerge to hunt for grasshopper eggs to feed on. After several weeks of feeding, the larvae turn dark in color and pupate until their final stage.  

After 10 days, an adult blister beetle emerges to feed and reproduce during their 3-month life cycle.  

To prevent a blister beetle attack, hay farmers should inspect their crops since the pest clusters in groups as they feed. Those who purchase hay for their animals whether for food or bedding for winter should inspect the hay bales before purchasing if blister beetles are a common problem where they live. 

Blister beetles love garden leaves of all kinds. The pesky insects can be found munching on tomato, potato, eggplant, peppers, and leafy green vegetables in mid to late summer.  

The beetles do have a beneficial side because of their love for grasshopper eggs. Grasshoppers can be destructive to farmlands and gardens, but the blister beetle's larvae will feed on grasshopper eggs, therefore reducing the damaging insect. 

However, the blister beetles do not consume grasshoppers or their young and can be dangerous in their adult stage. And once mid-summer comes along, chances are the damage has already been done to vital food gardens and hay crops. 

If the destruction has already been done, it's best to rid the area of damaged plants and as many beetles as possible by hand. 

When picking blister beetles and their young by hand, always wear gloves, and drop the pests into a bucket of warm soapy water to eliminate them. 

 If the pest does happen to fall into the soil, they can still be picked since they tend to lie still when there is danger. 

Keeping your garden and its edges neat and trimmed from debris and weeds can help reduce a beetle infestation. Weeds such as ironweed and pigweed attract blister beetles, so if possible keep it out of your yard and garden. 

Birds can be man's best friend and a  blister beetle's worst enemy if allowed. The birds will pluck the pests off of your plants and feast on them. 

Because of their love for grasshopper eggs, blister beetles will often be found where there is an infestation of grasshoppers. Keeping them under control can help keep blister beetles down.

Hay crops are especially susceptible to both insects, so where there is an infestation of grasshoppers, blister beetles are likely to follow. If possible keep damage to a minimum by avoiding equipment and tools that may crush the beetles. Early season harvesting of hay is best since the pests are at a minimum during the cooler months.