What Do Blister Beetles Eat? What Crops Can They Damage?

Blister beetles are plant pests, and you should try to remove them if you spot them in your yard. So, what do blister beetles eat? Which plants are at risk from them? Let’s find out.

Anytime you see a brightly colored beetle, take it as a sign of their toxicity and stay away!

One such beetle is the blister beetle.

Their name comes from the painful blisters they can cause on human (and animal skin).

Blister beetles produce Cantharidin as a defense mechanism against predators (and their bodies continue to secrete this, even when they die).

These beetles are pests that feed on flowers and sometimes tender shoots, with the instars feeding on insect eggs.

They also love munching on crop plant leaves, such as those of tomato, potato, eggplant, beans, and peppers.

In this article, we will talk about what these beetles eat and who eats them.

What Are Blister Beetles?

Blister beetles are soft-bodied insects belonging to the Meloidae family.

There are over 2500 species of blister beetles, with 26 found in Florida, the US itself. Moreover, they have multiple subfamilies and genera within these species.

These beetles have soft, elongated bodies, with a head that is bent downwards and a thin neck portion.

Likewise, they’re quite similar to beetles from the Oedemeridae, which are known as false blister beetles.

What Do Blister Beetles Look Like?

Beetles of the Meloidae family can have a variety of colors, depending on the species.

Some Common Blister Beetle variations are gray bodies with black marks, fully black bodies, ash gray bodies, and brownish-reddish bodies.

Some species, like the Hycleus lugens have bright yellow dots to warn predators of its toxicity.

Some, like the Pyrota lineata are orange in color with black striations on their bodies (striped blister beetles).

Under the subfamily of Meloidae, we have various types of blister beetles tribes, such as Cerocomini, Epicautini, Eupomphini, Lyttini, Meloini, Mylabrini, and Pyrotini.

The larvae of all species look similar – with a boat-shaped body and setation patterns on their bodies.

A common way of distinguishing the larvae from that other beetles is that they have only one or two stemmata (eyes) on the sides of their heads (as opposed to other species, which have four or five).

What Do Blister Beetles Eat?

Blister beetles have a diet that varies as they move on from instar phases to an adult.

As adults, they are generally found in fields with flowering plants, but as larvae, they are predaceous.

What Do Adult Blister Beetles Eat?

Blister beetle adults mainly feed on flowers. Some common plant families they attack are Amaranthaceae and Leguminosae.

Some adult beetles also eat soft leaves or tender-shoot plants. They usually attack plants in a swarm.

This is commonly seen in beans. Blister beetles of the Epicauta subfamily are known to eat plant leaves.

Apart from flowers, they also attack the leaves of various plants.

What Do Blister Beetle Larvae Eat?

In their larval stages, blister beetle instars feed on the eggs of the acridid grasshoppers.

Some larvae, during their first instar stage (also known as the first grub phase or FG phase), feed on bees.

Larvae do not generally harm plants.

Some feed on the eggs laid by other blister beetles.

Feeding on eggs of other species is also common. For e.g., larvae of the Epicauta species have been found within the egg nests of the Melanoplus species.

Are They a Serious Crop Pest?

Blister beetles can be a serious crop pest, depending on the specific species and the crops they infest.

They attack the leaves of plant crops such as tomatoes, potatoes, eggplants, beans, and peppers.

Several species of blister beetles are known to damage tender crops, such as alfalfa and beans.

When these beetles feed on crops, they can cause defoliation, stunting, and even death of the plant.

In addition to damaging crops, blister beetles can also pose a risk to humans and animals, which we will discuss next.

How Blister Beetles Can Be Bad For Livestock

Apart from the fact that they can cause blisters in humans, blister beetles are toxic for livestock and poultry.

Their bodies secret a chemical called Cantharidin. Cantharidin oil is obtained from the bodies of crushed beetles.

This oil can poison livestock, and the amount produced by a total of 30 to 50 beetles can be fatal for even a horse!

Some common symptoms of this poison are sores in the cattle’s mouth and body, blood in urine and stool, colic, and depression.

To prevent blister beetle poisoning, it is important to ensure that they are not hidden within hay bales.

They can easily get crushed and poison the bales.

If you have alfalfa fields, harvest before bloom to prevent infestation, which can help prevent deaths in horses.

How To Prevent Blister Beetle Infestations

If you want to secure your crops and livestock, here’s what you can do:

• Diatomaceous Earth – You can sprinkle the Diatomaceous Earth mixture near the roots of your plants. This siliceous earthy mixture will kill existing beetles and prevent future infestations.
• Oyster lime shell – Similar to Diatomaceous Earth, you can prepare the soil with oyster lime shell mixture before planting to prevent beetle growth.
• Neem Oil – Spray a mixture of neem oil and soapy water onto the beetles. Make sure to protect yourself with gloves and the necessary clothing during this. The mixture will make the beetles sterile.
• Manual extermination – With the proper gear, you can exterminate the existing beetles by hand after stunning them using the neem oil mixture or pesticide. After you collect them, drown them in a soap-water mixture. Make sure to remove any clusters of eggs as well.

Beneficial Insects That Can Help Remove Blister Beetles

Alternatively, you can try getting rid of them in an organic way:

• Common predators of the blister beetle include small reptiles, including frogs and lizards
• Some birds, and smaller mammals can also feed on them.
• Larvae of some insects, such as Lacewings, are known to prey on the grub of beetles.
• Starling and robins are birds that commonly eat beetle grub.

Frequently Asked Questions

Wrap Up

Blister beetle grub can also be beneficial since they eat up grasshopper eggs.

In fact, as long as you don’t have flowering plants and cattle, you might even prefer having them around.

However, the adults are ferocious eaters of crop plants, including potatoes, peppers, tomatoes, or any other plant that has leaves.

They also attack some common ornamental flowers.

Moreover, these bugs are particularly dangerous to livestock because they emit Cantharidin, a poisonous substance.

It is best to try and get rid of them. Smaller reptiles, such as frogs and lizards, can do the job for you. 

Lacewing larvae are also good at feeding on the larvae of these beetles. You can introduce them to your garden to get rid of blister beetles.

Thank you for reading.