Facts, Identification & Control
Beetles belong to the insect order Coleoptera. This is the largest order of insects. There are more than a quarter million species of beetles in the world. In North America, scientists have identified more than 25,000 beetle species.
Sometimes people mistake cockroaches for beetles. If the beetle is an adult, it can usually be identified by looking at the wings.
The front wings are called elytra. These front wings are often very hard and appear more like a shell than wings. The beetle folds the front wings so they cover the back wings. Most adult beetles seem to have a line down their back where the two front wings meet. Beetles come in many shapes, sizes and colors. Some, like the click beetles, are long and slender. Some beetles like lady beetles and June beetles (also known as June bugs) have an oval or rounded shape. There are even beetles that resemble spiders.
Behavior, Diet & Habits
Beetles develop in a four-stage life cycle. Scientists call this a complete metamorphosis. The stages are egg, larva, pupa and adult. The length of the life cycle also varies according to the type of beetle. Some beetles develop very quickly and they can produce more than one generation each year. Others, like some of the wood-boring beetles can take several years to decades to develop from an egg to an adult insect. The length of the life cycle also depends on the amount of food that is available for the larvae to eat as well as environmental conditions.
Beetles feed on many different plant and animal materials. Adult beetles often deposit their eggs near the food that the larvae will eat when they come out of the eggs.
Some beetles can become destructive pests. Carpet beetle larvae eat natural fibers and feathers. They often damage woolens and other fabrics. Other beetles, like powderpost beetles, feed on hardwoods and bamboo. These pests attack furniture and other items made of wood.
Some, like the flour beetles and the grain beetles, attack food products in homes. They also damage food in production facilities and stores. Some beetles damage lawns and landscapes. Immature June beetles, called grubs, attack the roots of grass. The elm leaf beetle damages trees by eating the leaves.
Many beetles are beneficial insects. The lady beetle (often called ladybug) feeds on plant pests like aphids and mealybugs. Gardeners appreciate these beetles and try to keep them in the garden.
Sometimes beetles, including lady beetles and ground beetles, can become nuisances. In the late summer and fall, homeowners can find hundreds of these beetles clustered on the outside of the home. The beetles are trying to invade homes for shelter through the winter or are looking to escape inclement conditions.
Types of Beetles
American Spider Beetles
American spider beetles are shiny and reddish brown to almost black. When viewed from above, they resemble a spider.
Asian Lady Beetles
Asian multicolored lady beetles are small and round-to-oval insects. They are usually red or orange, but they can be yellow, brown, or black.
Asian Longhorned Beetles
Adult Asian longhorned beetles are less than 5 cm long. They chew “galleries” into the inner parts of trees that can cause the trees to lose nutrients.
Blister beetles are approximately 1 to 2.5 cm in length, depending on species. These beetles are known for their production of a chemical called cantharidin.
Cigarette beetles are often light brown. These beetles fly and can “play dead” for a few seconds if they are disturbed.
Dried Fruit Beetles
Dried fruit beetles are small oval black insects. They have two amber-colored spots on their wings, and their legs and antennae are often reddish or amber.
Drugstore beetles are small, brown and oval-shaped pests that are typically about 2 to 3.5 mm long. They have been known to infest many household items such as cereal, spices, books, leather and more.
Elm Leaf Beetles
Elm leaf beetles are only about 5 mm long. They are yellow to olive colored and have a dark band on the outside of each wing.
Flour beetles are about 3 to 4 mm long and are reddish brown. They are common in homes and grocery stores and are often found in flour and cereal products.
Foreign Grain Beetles
Foreign grain beetles are reddish brown. These beetles are often found in homes and businesses that have moisture or fungus problems.
Japanese beetles tend to be agricultural pests. They have a metallic green body with copper-brown wing covers.
Larder beetles are usually black and have yellow bands across their wing covers. There are also several dark spots in the yellow area.
Plaster beetles are very small and less than 1 to 3 mm long. They range in color from yellowish brown, to reddish brown, to almost black.
Sawtooth Grain Beetles
Sawtooth grain beetles have flat bodies and are about 2.5 to 3 mm long. They have six tiny projections on each side, just behind the head.
Shiny Spider Beetles
Shiny spider beetles are small insects that range in size from 1 to 5 mm as adults. They are often dark red or black.
Beetles belong to Order Coleoptera. Comprising over 350,000 species, this is the largest of all insect orders. Beetles may live in a variety of environments, including underground tunnels, water, dry land and indoors.
Ranging from 1 mm to 15 cm in length, certain tropical beetles are the largest species recorded, while the feather-winged beetles are the smallest. Weighing up to 100 grams, the African goliath beetle is perhaps one of the heaviest insects worldwide. Certain longhorn beetles can grow to reach in excess of 15 cm in length, making it one of the world’s longest insects.
Insects that are commonly called fireflies are actually a species of beetle capable of illumination through the use of chemical-bearing segments upon the abdomen. Other beetle species, such as the certain click beetles, are also capable of producing light.
Beetles have well-developed antennae and chewing mouthparts, as well as shell-like front wings known as elytra. These wings form a straight line down the adult beetle’s back. They are durable and waterproof, serving as protection against damage and dehydration. However, unlike many other insects, most beetles are poor fliers.
Beetles feed on plants, small insects and animal fibers, depending on species. A few beetles are considered pests in gardens and crops, although some species, such as the ladybird beetle, may benefit humans by killing harmful insects.