Black Carpet Beetle
The black carpet beetle is one of the most common large, black beetles in Pennsylvania. The larvae consume almost any type of animal matter such as wool, silk, hair and leather. The black carpet beetle can be a pest in kitchen cupboards as well. The beetle lays its eggs in lint around duct work, baseboards or closets. Unlike adults, larvae avoid light. Black carpet beetles usually spend the winter in the larval stage and feed on dried dog food, old woolen fabrics or carpeting. Fully developed black carpet beetles live from two weeks to several months.
Black Ground Beetles
Many black beetles are commonly mistaken for the common black ground beetle. The nearly all-black insect has dark reddish-brown hues on its antennae and legs. These large black ground beetles feed on garden pests such as aphids and slugs. Originally introduced from Europe, black ground beetles are now abundant in woods, fields and gardens in Pennsylvania, most likely under fallen trees, leaves and stones. They can grow to be more than 1/2 inch in length. Because they do not fly, ground beetles have a number of predators including snakes and birds.
American Oil Beetle
Pennsylvania may not have fields pumping oil, but it does have many types of fields producing pollen. The American oil beetle, attracted to nectar and pollen, does not fly and is a very slow mover, so it has many predators. One-quarter to three-quarters of an inch long, the American oil beetle's shell resembles overlapping plates, which cover the insect's heavy abdomen. The shell appears dull black, iridescent black or dark blue.
Soldier Beetle
Also known as the Pennsylvania leatherwing beetle, the soldier beetle is commonly found in parks and fields. They resemble their cousin, the common firefly, but do not light up. Growing to 1/2 inch in length, soldier beetles feed on the pollen of milkweed, hydrangea and goldenrod. They also eat garden pests, supplementing their diet with eastern tent caterpillars, aphids, spider mites and other insects and their eggs.
Giant Water Bug
Found living in Pennsylvania ponds, slow-moving streams and shallow waters with vegetation, the giant water bug is aptly nicknamed "toe-biter" due to the defensive, painful bite it can inflict. The giant water bug can resemble a dead leaf, which aids in camouflage, as it plays dead to escape predators. The large, black beetle measures 1 1/2 to 2 1/2 inches, not including its legs. It has recognizable foreleg pincers and a flat, elliptical shape.
Black Blister Beetle
Blister beetles are a problem for farmers and gardeners. Growing to 3/8 inch to 1-inch long, they feed on leaves on the tops of plants but also are attracted to flower pollen and nectar. Female blister beetles lay their eggs in soil where the hatched grubs eat plant roots. The adults contain a toxin in their blood, cantharadin. This poison causes skin inflammation and blisters, hence their name.