There are more species of beetles in the world than any other insect or animal. They are found across the globe. Many species reside in Michigan, some of which are beneficial and others that tend to be pests. Michigan beetles are diverse and varied, exhibiting attributes held by different beetles around the world.
Michigan beetles come in a variety of sizes, though few are overly large. Take the emerald ash borer, for instance. Adults of this species grow to only one-sixteenth of an inch long. Four times as long, at a quarter of an inch, is Hungerford's crawling water beetle. The lady beetle species in Michigan are also very small. The larger ones are the Asian lady beetles, which grow between 4 and 8 millimeters. Small black lady beetles are only about 1 1/2 millimeters.
In the same way Michigan beetles vary in size, so do they vary in appearance. Lady beetles are round with a domed shell, split down the middle, which opens apart to reveal wings underneath. The twice-stabbed lady beetle is all black with two red spots. The Asian lady beetle has a black head and an orange or light red body covered in black spots. Emerald ash borers have an elongated, dark green body with light yellow or gold markings near the head.
Beneficial Beetles and Pests
Some beetles, like the lady beetles in Michigan, are beneficial. The twice-stabbed lady beetle was purposely imported from Korea as a biological control agent for euonymus scale. Asian lady beetles were brought in 1916 to control various pest species, too. They feed on mites, aphids, scales, mealybugs and various soft-bodied insects. At the opposite, pest of end of the scale is the emerald ash borer. Beginning around 1997 or so, these insects found their way into Michigan and since then have destroyed millions of ash trees in at least six southeastern Michigan counties.
Asian lady beetles are some of the most common in Michigan. Since they were brought to the United States, they have flourished throughout the country. They tend to overwinter in homes and are a common sight in rural and urban locations. Bathrooms, kitchens and bedrooms are likely places to find them. Hungerford's crawling water beetle, on the other hand, is not only one of the rarest beetles in Michigan but one of the rarest animals in general. They live in cold, clear streams and are known to populate only two sites in northern Michigan in addition to one site in Ontario.