On one of those glorious fall days recently, I took Dave and Clancy for a walk. As we strolled along the road, the breeze from the south ruffled my hair and extinguished the sound of the interstate a mile to the north. It carried the scent of ripening corn. Close by the crickets and katydids in the grass filled the world with their chirps and buzzes, and an occasional bird cheeped to its kin. Off to the side I could hear a combine harvesting the neighbor’s corn field.
And then something bit me on the neck. Ouch! I couldn’t slap at it quickly as I had a leash in each and, and then I felt another bite on my arm. I felt several of these pricks as I walked past the cornfield.
Most likely I was being bitten by one of a few species of insects commonly called no-see-ums. They’re called that colloquially because they are very small, and hard to see. Based on the fact that I had no evidence of the bites later in the day, I presume they were the tiny bugs called either minute pirate bugs or insidious flower bugs. Either name refers to Orius insidious, a bug about a fifth of an inch long that feeds on aphids, thrips, psyllids, small caterpillars, whiteflies, and insect and mite eggs. These tiny biters were probably just being displaced from the cornfield where they had been happily eating corn earworm eggs and small insects living on the silks. When the combine came through picking the corn, it caused a massive disturbance in the field, displacing the minute pirate bugs and everything else that was living there.
These little predators get their name from their coloring. A shiny black background with lighter markings reminded somebody of a pirate flag. Only about two millimeters long, the adults are more or less shaped like a flattened oval. They are true bugs, so they have a long piercing/sucking stylet that they use to puncture their prey and drink its fluids. The stylet is rather dull at its tip, so when these little pests “bite” me, they actually are just probing my skin to see if I’m a likely meal. I’m not, and my skin is too tough for them, so they move along, leaving little or no evidence that they had attacked me. Unlike mosquitoes and biting midges, they don’t inject anything either. They’re not looking for me. They’re looking for thrips, aphids and other soft-bodied pests. They’re likely to find them in flowering shrubs and weeds and other crop fields such as soybeans, strawberries and alfalfa.
Minute pirate bugs are generally considered to be beneficial insects and are sometimes released in greenhouses to keep the thrips and aphids under control. Unfortunately, insecticides aimed at plant-destroying insects also kill these little predators.
Minute pirate bugs lay their eggs inside plant tissues. The eggs are clear, so if you have a microscope, you could actually see the embryo’s eyes through the shell. Incubation takes about a week, and then the nymphs hatch, molt five times over the next two weeks and become adults. As adults they’ll live for three or four more weeks, eating voraciously. They can, for instance, eat up to 30 spider mites per day.
There’s another type of insect called no-see-ums because they, too, are only a couple millimeters long as adults. They’re not quite as benign as the pirate bugs though. They are tiny flies also known as biting midges. They belong to the same order (Diptera) as flies and mosquitoes. Like mosquitoes, these little horrors need a blood meal to produce their eggs. They get it by biting people and other mammals, birds and amphibians, and in the process they can spread diseases. These tiny flies are gray with species-specific patterns of hairs on their wings. Like the pirate bug’s exploratory poke, when they bite, it stings and burns like crazy. And then it leaves a telltale welt.
This one was too good to pass up. 100-plus-million-years-old fly, encased in amber (fossilized tree sap). Another find from Wikimedia.org, it’s titled, “Early Cretaceous Myanmar amber biting midge.” In line photo from Wikimedia.org by George Poinar Jr.
Minute pirate bugs tend to be out during the day, while the biting midges stick to the dusk to dawn cycle. Insect repellants don’t work on either type of no-see-um. The pirate bugs do tend to prefer light colors, though, so wearing darker colored clothing is said to help keep them away.
Feature photo from Wikimedia.org by Jack Dykinga Alt text: Minute pirate bug feeding on baby flies on a green leaf, according to the Wikimedia caption. Small, oval-shape insect with a bold crossing pattern on its folded wings. Its stylet (straw-shape mouth structure) is extended and working on dinner.