June beetles are starting their brief adult lives
Late on a recent star-lit June night, after enjoying another campfire near the lake, it came time to turn in. Over the course of the hours after dark while sitting beside the fire, I observed many a hapless June beetle, or June bug as they're also called, fly kamikaze-like into the flames and embers -- undignified ends to otherwise brief life cycles.
As I strolled across the backyard on my way to the house, the cool black calm of nightfall compelled me to stop, listen and gaze at the stars. It was, without exception, a magnificent early summer night. I immediately became aware of being surrounded by June beetles in flight. They were virtually everywhere my ears could hear.
The experience was nothing short of amazing. The hum of hundreds of flying June beetles, their buzzing wings whirring through the still air, was an audible spectacle to be sure. Some of the beetles came within inches of my head as they sped past, while others were aloft at greater heights. Some were landing in the tall grasses and trees, while others sounded as if they were crash landing and smashing into various objects. There seemed to be a sense of urgency to it all, yet none of the beetles was going in any particular direction.
June beetles belong to a large family of beetles, Scarabaeidae, which are included in the impressive order Coleoptera. The genus, Phyllophaga, includes many species. And though most people refer to June beetles as June bugs, the insect is not a bug at all. Bugs have sucking, or piercing, mouthparts, whereas beetles have chewing mouthparts.
Another major difference between bugs and beetles are found in each of the groups' wings. Beetle wings are contained underneath hard shells, or elytra, as these shells are called. The hind wings, which are membranous and folded underneath the elytra, are not visible until the beetle prepares to fly. At such time, beetles open their elytra to expose their hind wings and accomplish flight. Bugs' wings, on the other hand, if they have wings, have no covering, and are usually membranous.
Other differences between bugs and beetles can be observed at their respective stages of development. Bugs undergo incomplete metamorphosis, where juveniles resemble adults, are smaller and have no wings. In contrast, beetles undergo complete metamorphosis such as what butterflies and dragonflies go through. Beetle larvae are worm-like grubs with hardened heads, chewing mouthparts and legs.
And such is the life of the June beetle. Their entire life cycle, depending on the species, can be as short as one year and up to four. Emerging from the ground as fully developed adults on warm spring nights, June beetles begin to seek mates almost immediately.
Adult June beetles appear black in color, but are actually reddish-brown. At about a half-inch to 5/8-inches long, June beetles are fairly large in size as insects go. Ask anyone who has experienced a collision with a June beetle while riding a motorcycle and they'll tell you that June beetles can hurt.
As most people know, June beetles are attracted to lights. During large flights, it's not uncommon to have tens of dozens of beetles banging relentlessly into the windows and screen-doors of our homes on those spring nights when the beetles emerge. Apparently, females, for whatever reason, are less attracted to lights. Perhaps their main intent is to lay eggs, which of course is what they seek to do.
If you observe these fascinating insects long enough, you will eventually discover that females are the beetles that dig into the ground. She'll dig up to five inches below the surface to drop their eggs, at which point she exits, leaving her eggs to develop on their own, and resumes her short life by feeding on the leaves of trees at night and resting during the day.
Three to four weeks later the "C"-shaped, white-colored grubs hatch and begin their three-part larval development. The first two stages, or "instars," as each of the stages are also called, lasts approximately three weeks each. The third stage lasts the longest.
The larval June beetle's third and last instar continues inside the earth throughout the summer and autumn until the following spring. And, as many of you come to expect, adult June beetles begin emerging in late spring and early summer. Prior to the adults' emergence, larval June beetles pupate some 3-6 inches deep in the soil where they remain for another three or so weeks until, at last, when conditions are right, the adult beetles appear en masse.
June beetle larvae -- those white grubs with hard heads and odd-looking legs -- are eating machines as they grow and develop. In some extreme cases, June beetle larvae can destroy lawns through their feeding and tunneling activities on the roots of grasses. In such instances, whole lawns can turn brown and not green up at all the following spring.
Indeed, another rite of passage is occurring in the natural world. These night-flying insects that some people call bugs, but are really beetles, are out and about every year around this time. Their appearance, which lasts for only a short while, will assure that, once again, more June beetles will emerge next spring as we get out and enjoy the great outdoors.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at firstname.lastname@example.org