Keep and eye out for these native, yet rarely-seen insects
Story and Photos by Dr. Blake Layton
Have you gotten to spend a lot of time outside in the yard and garden so far this year? If so, you have probably seen a lot of insects. Most of these were probably pest insects, but you may have also noticed a lot of butterflies, maybe a few moths, and some of the more conspicuous beneficial insects, such as bees and lady beetles.
Some insects are much more common than others. If you were participating in an insect scavenger hunt, it probably would not take you very long to collect a fire ant and a mosquito, but you would likely have to search for a long time, and be very lucky, to collect any of the insects discussed here. These are all large, conspicuous, native insects that occur throughout the southeastern U.S., but they are just not very common. None of these are pests of plants. Most are just rarely seen, but interesting, miniature wildlife. As a professional entomologist, I have not encountered any of these insects outside in a natural setting more than a half dozen times in my career, and most I have seen only once or twice. How many of these creatures did you see this year? How many have you ever seen, even once, in your lifetime? Keep your eyes open – the season is not over yet.
Eastern Hercules beetle (Dynastes tityus)
In terms of sheer weight, eastern Hercules beetles are the largest insects in the eastern U.S. Adults are most often encountered around the outsides of buildings where they have crash-landed after being attracted by lights at night. These big beetles can and do fly, another good reason for motorcyclists to wear a helmet with a face shield! Only the males have those large horns on their head and thorax. Except for the absence of horns, females are similar in size and appearance. Both sexes vary in color, from the mottled green of the specimen shown here to a uniform dark brown. Gardeners sometimes find the larvae in decaying logs or tree stumps. They look just like the white grubs you might find while digging in the flowerbed, but are much larger; four or five mature grubs are a double handful. People who rear beetles as a hobby sometimes keep eastern Hercules beetles as pets. Yes, there really are such people. This hobby is especially popular in Japan, where there are specialty shops that cater to these hobbyists.
Railroad worm (Phengodes spp.)
Railroad worms are colorful in the daytime, but they are even more spectacular at night because each body segment has spots that glow in the dark. As one moves across the ground, it looks like a miniature passenger train with lights glowing through the windows. It’s not the orange spots that glow, but other areas on the body. Don’t confuse these with fireflies and their larvae, which are known as glowworms. Although they share the ability for bioluminescence, railroad worms belong to an entirely different family of beetles and they are much less common than fireflies. Granted, this mature female does not look much like a beetle; adult female railroad worms retain the form and appearance of the larvae. The winged males don’t look a lot like beetles either. Their forewings are greatly reduced and they have large conspicuous antennae. What do railroad worms eat? Millipedes. They trail them down, bite off the head and consume the insides, leaving the empty shell behind.
Eyed click beetle (Alaus oculatus)
Encounter one of these large beetles resting on the bark of a tree and you may feel like you are being watched. Those false eyespots are quite conspicuous, but the real eyes are much smaller. These are members of a large group of beetles known as click beetles. Place one on its back and it will flick its body in an attempt to right itself, making a distinct clicking sound as it does so. Click beetle larvae are known as wireworms and most wireworms live in the soil and feed on plant roots, but the larvae of eyed click beetles are predators that live in decaying logs and feed on the larvae of wood-boring beetles. However, this does not mean eyed click beetle larvae are “beneficial” because wood-boring beetles that feed in rotten logs are not pests. A few tropical click beetles have spots on their pronotum that glow in the dark, but the eyespots on eyed click beetles are not bioluminescent.
Wheel bug (Arilus cristatus)
Wheel bugs belong to a rather large group of predatory bugs called assassin bugs. Most assassin bugs, including wheel bugs, feed on other insects, but one sub-group of assassin bugs, known as kissing bugs or conenose bugs, feeds on the blood of vertebrate animals. Wheel bugs are the largest assassin bugs in the country, and a large adult can eat quite a lot. This one is eating a painted lady butterfly caterpillar, and while taking the photos I could see the caterpillar shriveling and shrinking as the wheel bug sucked out its hemolymph. Wheel bugs can and will bite. According to people who have been bitten, the bite is as or more painful than a bee sting, but wheel bugs are not aggressive, at least not toward people. Don’t handle them and they won’t bite you.
Eastern bloodsucking conenose (Triatoma sanguisuga)
These strikingly colored insects are in the same family as wheel bugs, but their diet is a bit different. As the name suggests, conenoses feed on blood – red blood. Their hosts include tree frogs, wood rats, raccoons, possums, dogs, and yes, even humans. The bite is usually painless because they don’t want the victim to realize it is being fed upon. They are also potential vectors of a serious disease of humans known as Chagas disease. But don’t panic. Incidence of Chagas disease is extremely low here in the U.S. Even though eastern bloodsucking conenose bugs are often infected with the organism that causes Chagas disease, they are not very good vectors for the disease. Chagas disease is much more common in Mexico and other Central and South American countries, where it is spread by a different species of conenose bug that is a more efficient vector. Although it is good to be aware that the eastern bloodsucking conenose can potentially harbor a serious disease, this is not something to lose sleep over. In the rare event you encounter one in your yard, just don’t handle it – the disease is spread through the feces. If you find you have accidentally crushed one, wash your hands thoroughly with soap and water.
Scorpionfly (Panorpa spp.)
Scorpionflies only look a little bit like scorpions and they can’t actually sting like scorpions. Only males have the large claspers at the end of their abdomen, which they use for mating and carry curled over their back in this scorpion-like pose. Why such a long face? Can’t really say, but they have chewing mouthparts at the end of that long snout, which they use to feed on dead insects and animals, as well as decaying plant material. As a key part of their mating ritual, male scorpionflies present the female with a small insect or special salivary secretion as a nuptial gift. Scorpionflies are most often seen in or near wooded areas.
Wood wasp (Sirex nigricornis)
Wood wasps are a special group of solitary wasps that live as woodborers during their larval stage. They are also called horntails because of that short pointed structure at the upper end of their abdomen. The longer, needle-like structure located below this is the ovipositor of the female. Female wood wasps use their ovipositor to drill into trees and logs to lay their eggs, and the resulting larvae feed by boring through the wood. This particular species is common throughout the eastern U.S., where it feeds on dead pine trees. A closely related non-native wood wasp, the European wood wasp, has recently become established in some areas of the U.S. and is causing concern because of its ability to attack and kill live healthy pines (Pinus spp.). We have several other species of wood wasps that specialize in feeding on other types of wood. As you might expect, wood wasps are most often encountered around woodpiles, logs, stumps, or standing dead timber. Wood wasps can and will bite if you handle them, but they can’t sting.
Giant ichneumon wasp (Megarhyssa atrata)
You might think wood wasp larvae living deep inside a log would be safe from attack by parasitic insects, but giant ichneumon wasps specialize in parasitizing wood wasp larvae. First they locate where the wood wasp larva is feeding inside the log; then they use that long ovipositor to drill through the wood and deposit an egg on the helpless larva. The ovipositor of this particular wasp was 41/4 inches long, but the ovipositors of some giant ichneumon wasps can exceed 5 inches. Only four species of giant ichneumon wasps occur in the U.S. One of these is being used as a biological control agent, both in the U.S. and other countries, for the invasive European wood wasp. The insect family Ichneumonidae contains thousands of species of wasps that specialize in parasitizing other insects, and this is one of the most important groups of beneficial insects. Most species of ichneumon wasps are much smaller than this one.