Interesting Insects
Gardeners’ lives are heavily influenced by insects. Mosquitoes invade their space, Japanese beetles ravage their plants, borers bore, caterpillars chomp, stink bugs stink, and the list goes on. There are a wealth of beneficial and fascinating insects that enrich the garden world.
Assassin and ambush bugs are generally beneficial and intriguing. There are more than 160 species in the family Reduviidae (including three-legged bug) in North America. Most assassin bugs are large (½ to ¾ inch) predators of crop pests, including caterpillars, leafhoppers, asparagus beetles, and webworms. While most are black or brown, some are very brightly colored. They have an elongated head and distinct “neck.” The long, curved mouth parts form a beak which is carried beneath the body, fitted into a special groove. This insect lays in wait for prey, pounces, uses their front legs to hold the prey still, inserts digestive enzymes through their beak to immobilize the prey, and sucks up the digested insides. While a valuable natural control for destructive insects, do not try to pet them—they will bite.
Although technically not an insect but an arachnid, the trap door spider (Ummidia) is one of the largest spiders native to Wisconsin. It bears a slight resemblance to a tarantula, but is smaller, measuring only 1-2 inches long. Unlike most spiders, this one does not spin a web. Instead, it spends its time either living in a burrow or making a new one. The web-lined burrow is capped with a hinged door from which it springs out to capture its prey. They are fast runners and have two large fangs to subdue their prey. This spider is seldom seen by humans as it lives in forests, tall grasses, and remote areas. If it does bite a human, it will hurt but not be fatal.
One of the largest and coolest looking insects in Wisconsin is the Scarab beetle (Osmoderma). These beneficial insects help to decompose wood and are found in tree cavities filled with debris. The larva grows up to two inches in length and seem to be in a permanent C shape. If found in a rotting tree, they are not the culprit for the demise of the tree but are performing a valuable service by returning the tree to the soil. They emit a strong odor of leather when captured, leading them to be referred to as the “leather beetle.”
The Luna moth (Actias luna) is a stunningly beautiful, nocturnal insect that lives in the adult form for only one short week. It has pale, fluorescent green wings with green, white, and brown faux eyes on each of their wings. This large (more than 3 inch) moth has feather-like antennae and long, sweeping wing tails.
Lastly, another non-insect (actually a crustacean) is the roly-poly bug. These creatures bring out the child in everyone; who can resist giving it a poke to see it roll up? They are harmless, soil-inhabiting isopods that feed on decaying matter in the soil, providing a valuable service to gardeners. They require moist conditions to live, so if they migrate indoors, they will not live long and can simply be swept up and disposed.
In each of these cases, there are captivating videos available of the insects in action. Take the time to do some research and check them out.
Carol Shirk, Certified Master Gardener