Common black beetles can be a bit tricky to identify because there are actually dozens of species referred to as common black beetles. Fortunately, these little black bugs don't really pose any sort of danger to human beings. Some of them can be annoying, since most people don't like to share their homes with bugs, but other species can really be quite beneficial. Some help you to keep your garden free from pests, like aphids. Most types of black beetles look very similar and can only be distinguished if you were to examine them very closely.
This common black beetle came over to the United States from Europe and now lives all over America. You can recognize the Pterostichus melanarius because it is about one inch long. It is black or reddish black and has very long wings. Most notably, is has lots of little ridges or grooves that run down its wings. These beetles usually live in your garden. They can be good for your garden because they eat pests, such as aphids and slugs. These pests could otherwise damage your plants. Sometimes the Pterostichus melanarius also eat helpful garden bugs, though, like earthworms and other beetles. Scientists are not entirely certain what this beetle's impact on our local environment is.
This black beetle is also known as a black carpet beetle and it is very common in Pennsylvania. Unlike the Pterostichus melanarius, the Attagenus unicolor is an annoying pest. It gets into people's homes and eats animal products. This could include leather, wool, silk, feathers, hair or some of your food. You can recognize the Attagenus unicolor because they are about one-quarter of an inch long and they have shiny, black carapaces, which are sometimes reddish-black. These beetles can fly and usually only live for a couple of weeks. They are attracted to lights and can be killed with pesticides.