What Do Beetles Eat?

When you contemplate what foods beetles eat, it is tempting to say “just about everything.” Beetles eat a wide range of things, from carrion and plants to carpet fibers, dung, and even the roses in your garden. However, not every beetle eats everything; many are quite selective in their diets.

Beetles eat such a wide variety of foods because there are so many of them. These robust insects have been around for at least 270 million years. There are over 400,000 species, which make up 25% of all animal life. They are found everywhere except the polar regions. Beetles come in many sizes, but their shapes are generally similar. They are usually rounded, have hardened forewings that must be raised for flight, and possess chewing mouthparts. Let’s check out what beetles eat.

What Foods Do Beetles Eat?

With over 400,000 species of beetles, it would be impossible to list every food item in every beetle’s diet. However, here are a few beetles whose diets are more specialized:

Dung Beetles

Dung-rolling beetles are a type of scarab found everywhere except Antarctica. Members of the Scarabaeinae subfamily exclusively eat dung. They get all their water and nutrients from their food source. These insects not only eat dung, but they are fond of rolling it into little balls. The female lays her egg in the center of the ball, and both parents bury it. When the grub hatches, it starts to eat the dung. One type of dung beetle navigates by the stars, but scientists don’t know how it knows to do this. Dung beetles are black, green, or bronze and range in size from 0.39-0.70 inches.

Carrion Clown Beetles

This little black beetle eats dead and decaying matter. It is partial to dead frogs and fish washed up on the banks of bodies of water. It is a tiny beetle, measuring between 0.18-0.20 inches long. It has short antennae and punctures in its upper wings that make it resemble a shoe button.

Carpet Beetles

The carpet beetle doesn’t actually eat carpet fibers — its larvae do. The larvae not only eat carpets, but clothing and upholstery if they are made of natural fibers such as wool or cotton. One thing that makes the larvae of this beetle so destructive is that they can remain larval for as long as three years. Ironically, the adults don’t eat, but the female can lay as many as 100 eggs.

Boll Weevils

Adult boll weevils eat the buds and the flowers of the cotton plant. Both the adults and the larvae infest the plants. Native to Mexico, this insect somehow got to the southern United States by the end of the 19th century and spent much of the 20th century devastating the cotton industry. Like other weevils, this beetle can be recognized by its long, curved snout. They are a grayish color and measure about 0.24 inches long.

Superworms

The larvae of Zophobas atratus, commonly called superworms, are the grubs of black beetles called darkling beetles. These grubs can survive on Styrofoam (polystyrene). They begin breaking it down by chewing it into small pieces with their mandibles, exposing the plastic to oxygen. Then, the bacteria in their guts produce enzymes that further degrade the polystyrene. Over a 28-day period, researchers found superworms could live on Styrofoam as the only item in their diet.

Although the foods they eat vary widely by species, beetles may also consume:

• Other insects, including bees, wasps, aphids, and other plant pests and their larvae
• Powdered milk, a favorite of the Pleasing Fungus Beetle
• Pollen
• Nectar
• Spiders
• Tree bark and heartwood, like the emerald ash borer larvae
• Flour
• Many types of flowers, buds, and leaves
• The wood of floors and furniture, like the pine borer
• Ripe fruit
• Plant roots, including root vegetables such as carrots (larvae)
• Decaying wood
• Fungi
• Small fish
• Snails and slugs

How Do Beetles Hunt Prey?

Beetles use a number of strategies for hunting prey. Sometimes, only the larvae actively hunt, as adults eat less because their focus is on reproduction. In other cases, both young and adults share the same diet. The ladybird beetle flies to places where prey is likely to be and lays her eggs under a leaf of the plant. When the larvae hatch, both the adult and the larvae consume aphids, scale insects, and anything else infesting the plant.

Scaphinotus angusticollis is a black beetle with long legs that’s found in North America. Flightless, it hunts and eats snails. It travels over the ground, looking under logs for its prey, and when it finds a snail, it uses its long mouthparts to reach into the shell and eat the meat. The beetle also feasts on easier-to-catch slugs and sometimes eats fruit.

Found in Europe and Asia, the great diving beetle is a big aquatic beetle that can grow to 1.4 inches long. It lives in fresh water and creates an air supply for itself by collecting bubbles that it tucks under its wings next to its breathing pores. While underwater, it hunts other aquatic insects, tadpoles, and small fish, snatching them with its powerful jaws. Males even have suction cups on their legs that let them hold on to prey, as well as to females.

Tiger beetles run toward their prey, stop, reorient themselves, then race after it while holding their antennae straight out in front of them to avoid obstacles. Tiger beetles are also strong fliers and can catch prey in flight.

What Animals Eat Beetles?

Beetles consume a wide variety of foods, and in turn, many animals — including humans — eat beetles. One great delicacy in Thailand is the grub of a Hercules beetle wrapped in banana leaves, roasted, then eaten with special sauce. The grubs of many beetles are edible, including those of weevils, longhorn beetles, and Japanese beetles. Other animals that eat beetles include:

• Mammals, including raccoons, rodents, foxes, and skunks, among others
• Spiders
• Other insects, including assassin bugs
• Lizards
• Birds
• Frogs
• Toads
• Snakes