Common Black Ground Beetle

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(Pterostichus melanarius)

Pterostichus melanarius

Feeding Habits

The Common Black Ground Beetle generally eats grubs, worms, maggots, and many other soft-bodied insects. They are mainly carnivorous and feed on mostly other insects. The feeding habits of this beetle are particularly beneficial to gardeners around the world. They feed on many insects that can be harmful to gardens or to home owners such as cutworms, fly maggots, caterpillars, aphids, weevils, slugs, and snails. The beetles habitat makes it easy for them to find prey, for the insects they eat are abundant in almost every environment. These beetles can not fly to hunt their prey, however they sometimes climb trees and shrubs to find prey to hunt. The Common Black Ground Beetles larvae are predatory like the matured beetles, they feel on worms and other insects that live beneath the soil.

Life Cycle

Like all beetles, Carabids undergo complete metamorphosis with four stages of development: egg, larva, pupa, and adult. The entire cycle, from egg to reaching reproductivity, takes a full year in most species. Female Ground Beetles can lay up to several thousands eggs during their lifetimes. The females lay their eggs in the late summer under the surface of the soil or they cover their eggs with soil. The eggs will then hatch after about a week and spend the winter under the soil. Larvae go through 2-4 instars before reaching the pupal stage. During each of these instars the larvae grow larger. The larvae of the Ground Beetles are somewhat flattened and have mobile behavior. They will become pupae by the early spring and begin to feed. They won't reach full maturity until the summer, which is when they emerge from the soil and start the cycle over again. Adult Common Black Ground Beetles live for about 2 to 3 years after they reach full maturity.
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Common Black Ground Beetles usually grow to the length of 1/2 to 5/8 inches.They have an extremely hard exoskeleton that is made up of many different small plates that allow the beetle to be protected while still maintaining flexibility. Like all insects the Common Black Ground Beetle has three different sections which are the head, thorax, and abdomen. These beetles have a distinctively flat head and large compound eyes. The antennae are used as a sense of smell and also for the beetles to feel the surrounding environment. The antennae of this beetle are mostly black like the rest of their bodies but have a tint of red or brown. The legs of the Ground Beetle's have adapted to be long in order to run at higher speeds away from predators. Their legs are also widened and have spines for more efficient digging. As with the antennae, the legs have a tint of red. The abdomen is covered by the hard-shelled wing covers that have ridges running along them. The body of the Common Black Ground Beetle is a metallic black with red tints in some spots. The larvae of these beetles are flattened and resemble worms. Click here to see what the larvae look like!

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Common Black Ground Beetles are found almost everywhere. During the day they hide underneath rotted logs, stones, and also piles of leaves. They inhabit woods and fields around the world. They are most often found in gardens hunting down harmful pests. Their preferred time to hunt is at night because they are nocturnal insects. The habitat these beetles live in is perfect for them because the food source is abundant.

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Geographic Range

The Common Black Ground Beetle is found in North America and in many places around the world. They are mainly found in cities and large towns instead of the country side.

Mating Behavior

The Common Black Ground Beetle, like many other beetles, is dependent on chemicals called Pheromones during the mating process. The Pheromones attract a mate to the beetle and the pair then the male pets the female with his antennae before they mate. If a female attracts more than one male, the males compete to win over the female and mate with her. The pairing is usually short but in some cases it may last for more than an hour until the sperm fertilizes the egg. After the female lays her eggs, there is no parental care from either parent of the offspring during or after their maturity.

Ecological Role

The Common Black Ground Beetle is considered a helpful creature in nature because they kill many plant killing pests. They are especially helpful in gardens throughout the world. They consume harmful insects including cutworms, fly maggots, caterpillars, aphids, weevils, slugs, and snails. Killing these pests allows plants in gardens to grow successfully. The Common Black Ground Beetle is also an important part of many animals indigenous to New Jersey and many other parts of the world. One example of an animal that preys on the Common Black Ground Beetle is the Wood Frog. Infact, Ground Beetles made the Top 10 Good Insects for Your Garden list!

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