Window on Nature
By Lowell & Kaye Christie, F47246
We’ve had a fascinating couple of months finding out about some of the weird insects that live in North America. Last month we wrote about cicadas, surely the loudest insect singers. This month we’ll start our discussion with walking sticks, and then talk about a few other odd insects we hope to see this year.
First of all, let’s address several misconceptions about walking sticks. First, a walking stick is not the same thing as a praying mantis, although they share certain similarities. Second, not all walking sticks bear any resemblance to a stick with legs. Although we’ve actually raised praying mantises, neither of us has ever seen a walking stick firsthand. So we’ve decided to dedicate this spring to finding them in every size and shape that we can.
While doing our research, we found that the walking stick is a very common insect, although it is often overlooked because of its excellent camouflage. Another reason entomologists don’t study it too closely is because it’s rather benign. For the most part, these insects are nondestructive vegetarians and pose few problems for farmers or people living in residential areas.
With more than 3,000 varieties of walking sticks, you would expect them to be found worldwide. This isn’t necessarily the case, however. Many can be found in tropical climates where insect variety is greatest, but there are also several interesting varieties here in North America.
Finding walking sticks is difficult in part because they remain motionless during daylight hours, hanging inconspicuously from a leaf or twig. After dark they venture out to eat, and then they pack it in by dawn.
The walking stick is one of a few creatures capable of partial regeneration. For example, when a walking stick’s leg is lost or damaged, it will gradually grow back during the next few molts. This shedding of skin (molting) isn’t exclusive to insects. Amphibians and reptiles also shed their skin as part of the growing process. Walking sticks, however, eat their own shed. Fortunately, larger animals don’t follow this habit, and we can use discarded skins as clues about what creatures inhabit the area.
Surprisingly, not all stick insects are thin and look like sticks, as their name implies. True walking “sticks” represent only a few of the 3,000 varieties of this insect in existence. Others have adapted their appearance to more closely fit their environment. For example, some walking sticks imitate leaves, whether in springlike green or a dried-out autumn brown. Others take on a big, fierce, ready-to-eat-you appearance. They’re just faking. These peaceful critters are relished by predators “” birds, rodents, reptiles, other insects, and spiders “” and have to put on this disguise for protection.
The predacious diving beetle is another common, yet rarely seen, insect. In fact, there are more than 500 kinds of diving beetles in North America. Because they’re nearly always underwater, they can be hard to find, but they’re well worth watching for. Some reports indicate that they move so fast you seldom notice them, but that hasn’t been our experience. Our favorite site for finding water beetles is in a shallow, sandy-bottomed stream a few miles from our home. We just sit or squat down, and relax. It isn’t difficult to spot a jet black, inch-and-a-half-long, oval-shaped beetle against the pale-colored sand.
Although these beetles thrive underwater, they still need to breathe. To take on oxygen, a beetle will swim to the surface where it will trap an air bubble under its wing covers. It then dives with the bubble still in place and conveys the air to its breathing apparatus while underwater.
As their name implies, these beetles are predators, catching and eating other water insects, insect larvae, and even small fish. Adult predatory diving beetles swim well enough to catch most of their prey alive. Depending upon the prey’s size and texture, the beetle may eat it whole or tear it into bite-sized pieces before gulping it down. When food is scarce, predacious diving beetles will scavenge for and feed on dead creatures they find.
Even the larvae of these beetles are voracious eaters. They lie in wait near the water surface and snatch their prey with pincers. Diving beetles catch prey in their strong jaws, which are hollow and function like hypodermic needles. The beetle injects its intended meal with digestive juices, then it sucks the insides out.
Most predacious diving beetles hang out in wetlands and small lakes and are excellent swimmers. They search for their prey near vegetation and woody debris, which also provide them with cover. When a diving beetle locates a potential meal, its smooth body permits it to jet through the water and snatch the tasty morsel.
Adult beetles hibernate in soil below the waterline for much of the year. Like other critters, these beetles instinctively know when spring arrives and emerge to feed on insects.
If you see a large predacious diving beetle larva floating around in the water, be careful. The large pincers so useful in catching prey also can inflict a painful nip. Still, you aren’t likely to catch one of these guys “” they just swim too fast.
Our final guest this month is a bug that’s received a bad rap. When we were kids, spittlebugs, also known as froghoppers, were rumored to spit at predators and people who intruded into their lives. This, of course, is not true. Yes, they do produce spittle, but not to project at someone or something.
Even though there are 23,000 species of spittlebugs worldwide, few humans have ever even seen one. This bug uses its spittle as a place to hide, for a bug unseen is a bug uneaten. Creating the hiding spot is quite a process. First the spittlebug produces a liquid concoction that it whips up into a frothy mass of bubbles. When the bubble blob is large enough, the spittlebug wades right into it, adding more bubbles so it is hidden from sight. The mass is called spittle, thus giving the bug its name.
Finding a spittlebug takes knowledge and patience, since they spend most of their lives safely hidden inside the spittle. Predators can’t see them or smell them. The spittle also insulates them from heat and cold and helps keep them from drying out.
This spring, we will aspire to see our first spittlebug. If you should happen to run into a man and woman poking around globs of spittle to see what might be inside, there’s a good chance that it’s us.