Ground beetles are common bugs that you will see in your garden, especially at night. They are beneficial insects that will feed on garden pests. The adults are typically generalist predators in the garden. Their larvae can be more specialized in what they eat. Larvae can also eat other beetle eggs.
Though the common ground beetles eat small insects, other species have been known to eat slugs, snails, and even earthworms. These beetles are important for garden pest control, as they prey on some of the most troublesome pests.
Identification of Ground Beetles
There are about 40,000 species of ground beetles worldwide. Identifying these insects can be difficult because of their similarity to pest beetles. [1]
Larva
- Ground beetle larvae are usually brown or black.
- They have hard, joined shells.
- They have large mandibles (jaws) that are used to catch prey.
- Larvae can be up to 0.75 inches (19 mm) long.
Pupa
- Ground beetle pupae look like adults but are soft and white.
- They have a head, thorax & abdomen visible outside the shell.
Adult
- Ground beetles are shiny, hard-shelled beetles.
- The majority of them are black or brown, metallic colors.
- Some species can be metallic green, gold, red or blue.
- Most are up to 1 inch (25.4 mm) long, but some species can be 1.5 inches (38 mm) long.
- Ground beetles have oval bodies.
- They have 6 legs and long antennae.
- These beneficial insects have smooth elytra (wing covers).
- They have large mandibles (jaws) that are used to catch prey.
Life cycle of Ground Beetles
After the winter, females will lay eggs in the soil, under rocks, logs, or leaf litter. The larvae hatch from the eggs and start feeding on garden pests. The larvae will spend most of their time looking for prey under garden debris. They will feed until they pupate and then will emerge as adults.
Adult ground beetles, same as larvae, are nocturnal insects. During the day, they hide from predators by burying themselves in the soil, leaf litter, or under rocks and logs. Hunting mostly takes place at night. Some will climb trees, bushes, and crop plants, searching for prey. Some can survive by eating the seeds of garden weeds.
The beetle will go into diapause during the winter. It takes one year for the life cycle of these insects to complete, and they may live up to 2-3 years. Depending on the species, multiple generations may occur every year.
Pests Ground Beetles Control
Adults and larvae are both beneficial since they hunt a wide range of garden pests, including:
- Asparagus beetles
- Aphids
- Beetles and their Larvae
- Caterpillars
- Colorado Potato Beetles
- Corn Ear Worms
- Cutworms
- Fly Maggots and their Pupae
- Mites
A few species will feed on slugs, snails, and even earthworms using specially-adapted mandibles.
How to Attract Ground Beetles?
Diversity. There are no particular plants that attract these beneficial beetles. Still, it is known that high diversity of plants will be excellent habitat for them.
Protection. These beetles are nocturnal, so they will spend most of the day hiding in the soil, leaf litter, or under logs and rocks. By placing logs and rocks in your garden, you will provide shelter for them.
Untidiness. Encourage these beetles by leaving some of your lawn or garden untidy so they can access weed seeds and other food.
Interesting Facts about Ground Beetles
- Ground beetles are fast runners, some species can even fly, but they choose not to because their wings are too small to be effective.
- Sometimes you may find these beetles inside your house, but they do not bite humans nor cause any harm.
What to Do Next
Check out our other Beneficial Insects Guides. Read and learn more about how to identify their benefit and how to attract them.
Check out our Garden Pests Guides. Read and learn about how to identify and control garden pests.
Also, check out our Gardening Guides to learn easy step-by-step tutorials.
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