Tuesday, January 31, 2012

Insects Galore: A guest blog for Explore the Outdoors

This post was written as a guest blog for Explore the Outdoors, a program started by the Ohio Department of Natural Resources that endeavors to educate people about the natural wonders of Ohio. I highly recommend that you check out their website--it has great information on outdoor activities and state parks and reserves you can visit in Ohio. You can see my original post here.

Winter can be a beautiful time of year (when the weather deigns to give us snow), but if you're like me, it can also be pretty dreary for one important reason: there aren't many insects about. Sure, you might get lucky and find some stink bugs crawling around inside your house or come across a camel cricket or spider (not actually an insect, but an arachnid, of course) in your basement, but the assorted stragglers can't quite satiate the need to see our many-legged friends like the other seasons can.

If you haven't noticed yet, this post is going to emphasize how amazing the insects and other terrestrial arthropods are. First, let's establish some background. If you aren't already a fan of insects and would rather step on them than appreciate them, ponder this: out of all living organisms on the planet, over half are insects. Furthermore, out of all the animals, almost 75% are insects. When you include the other arthropods, it increases to 86%. Keep in mind that these are only species we have described so far: estimates predict that over 90% of all animals are insects. The sheer amount of diversity among the insects shows us that this is one important group. Keeping that in mind, let's explore the diversity of insects in Ohio.

Nature, and in turn, insects, are not things you have to drive to the outskirts of civilization to experience. It is (obviously) literally all around us, and this is especially true with regards to the insects. When I first learned of the total insect diversity, I was a bit skeptical. After all, I hadn't really noticed too much variability in the insects, other than mosquitoes could suck my blood, bees could sting me, and scarab beetles had a penchant for flying into porch lights during the summer. It wasn't until a few summers ago that I truly started looking for insects and observing the mind-blowing amount of variability there actually was. I started a personal project documenting the terrestrial arthropod diversity in my own backyard (I didn't want to make the spiders and millipedes feel left out) and have kept at it for three summers. I went through my yard a few times a week, taking an hour-long walk examining the trees, shrubs, and other vegetation during the day and night, just taking pictures and finding what I could. My current tally surprised me: to date, I have found over 100 different species.

The kicker? All of these insects, spiders, and millipedes have been found in an area only one acre in size. Now that's impressive! The phrase "backyard biology" has never been more relevant! But that's enough talk, it's time to look at some of the beautiful and interesting insects that Ohio has to offer.

First up is an ant.

  Well, not exactly. If we take a closer look, we learn...

 ...that it's not an ant at all! This is actually a jumping spider in the family Salticidae that mimics an ant, Synemosyna formica. I start off with this spider to illustrate two points. Firstly, that Ohio has some interesting and surprising diversity. Secondly, that it is important to pay attention. You'll find that these little critters can be surprisingly crafty, in a variety of ways. For example, a spider only has two body segments: the cephalothorax (head) and abdomen. In this species, its body is constricted to make it appear to have three body segments like an ant. In addition, it holds its front legs in front of its body, mimicking the antennae of an ant. You can see how small the spider is from the first picture: at most, these spiders will grow to just under six millimeters long. When I found this spider in my backyard, I thought it was an ant. That is, until it declined to run away like the other ants in the area. Instead, it stayed on the underside of the leaf I found it on, unmoving. This isn't ant-like behavior, so I caught it on the hunch that it might be something different.

Next up is an insect that a friend described as looking like "a Balrog that got hit with a sneeze of tie-dye." It may look ferocious, but it's actually harmless to humans. Other insects....well, not so much.

This is likely the biggest wasp you're going to find in Ohio: the giant ichneumon wasp, Megarhyssa macrurus. In this photo, it's inserting its three inch long ovipositor into the dead wood of a tree, in search of one thing: the larva of another wasp, the pigeon tremex horntail (Tremex columba). It can detect the wasp larva's movements in the wood, locate it, and then lay an egg next to the larva. Once the ichneumon wasp has done this, it will then sting the horntail larva, paralyzing it. Later, the ichneumon wasp larva will hatch and devour the horntail wasp, and continue to grow to adulthood.

With a lifestyle like that, it's a good thing this wasp is harmless to humans! It's difficult to convey in a picture just how beautiful this wasp truly is: the mixture of amber and yellow blend together to create one of the most jaw-dropping insects around. If you're walking in the woods and come upon some dead trees in a sunny area, search around a bit and you might be lucky enough to find one.

This next insect is a personal favorite of mine. It's a member of a fascinating family of bugs called the assassin bugs, a predaceous family that preys upon other insects. They are generally considered beneficial insects and are currently being studied for use in biological control regimes. Something called an assassin bug probably isn't going to be too peaceful, obviously, and these insects earn their name. They're ambush predators, and once some prey comes into their hunting ground, they creep up behind the prey and strike. They have a mouth like a straw, which they plunge into the unsuspecting victim, pumping it full of digestive fluids to paralyze and liquefy the insides of the unfortunate insect before sucking it out. Not exactly the most polite thing to do, but it's a way to make a living.

In Ohio, we're lucky enough to have the largest terrestrial true bug on the entire continent in our backyards: the wheel bug, Arilus cristatus. The picture above shows its namesake: a structure on the top of the thorax that looks like a cogwheel. This particular wheel bug has just emerged from its final instar (the fancy word for a juvenile stage in the life of an insect), hence the pretty salmon color. After a few hours, the color fades into a grayish black that camouflages the wheel bug against trees. The wheel bug can grow a little larger than two inches, making it a formidable predator. Its size allows it to take on large prey and equips it with the weapon to do so: its beak is longer than its head. This can be intimidating to humans, and the gut reaction of many people is to either run from it or squash it. This fear is not well-founded. While the wheel bug can indeed inflict a painful bite (being bitten by an assassin bug isn't even an entomologist's idea of fun), it will only bite when provoked. Even then, it might not bite. I've handled many wheel bugs and have yet to be bitten: the key is to respect it and handle it with caution. I wouldn't recommend handling a wheel bug, but it makes an interesting insect to keep in an enclosure (it's in a butterfly cage in the picture) and observe its habits. It's best to only do this temporarily and then release it to go on about its business, but it's a valuable learning experience.

No mention of Ohio's insect diversity would be complete without what many would argue to be the most beautiful moth in our area, the Luna Moth (Actias luna). I had a massive stroke of luck in my adventures this summer, with regards to this moth. I was researching assassin bug diversity at Marietta College's Barbara A. Beiser Field Station in early summer when I heard a strange sound coming from some grass. I bent down and searched for the source of the noise when something came crashing through the undergrowth.

A newly-emerged Luna moth was crawling towards me. There was no question that it had just emerged: its wings weren't yet pumped up, so it was in search of a tree to crawl up where it could safely expand its wings. Seizing the opportunity (as well as the moth), I placed it on a nearby maple tree and observed it for the next three hours. It takes a while for the moth to complete this task, and moths are at their most vulnerable at this stage: they can't fly away, and are nice protein-rich meals for any other animals that might happen upon them.

You can tell that this individual is a male, due to the thick antennae, which he uses to detect pheromones from the female: chemicals that let the male know where the female is located and if she is ready to mate. Adult Luna moths don't feed, focusing solely on mating to usher in the next generation. In fact, adults don't even have functioning mouthparts. Due to this, they only live for about a week, so mating is the top priority in such a short time.

The Luna moth is in the moth family Saturniidae, a group that includes the biggest moths in the world. The Luna moth is no exception, with a wing span reaching up to 4.5 inches. The wing span of the Cecropia moth, North America's largest native moth, is over 6 inches. Once you've seen these moths, you're not likely to forget them. They're attracted to lights, and are more abundant near forests, so start your searches there!

This is just a small sample of Ohio's insects: some are even more colorful and have novel life histories. I haven't even mentioned the beetles, which are the most diverse group of insects. In fact, one out of every four living things on Earth is a beetle. Isn't that marvelous?

In a few months, winter will be over and the insects will once again grace us with their presence. I encourage you to go outside and look around your own backyard to see what you can find. If you want to go further and identify what you've found, BugGuide is the best resource for North American insects on the web. If you want to go further than that, Nature 2.0 websites like Project Noah allow you to upload photographs of the organisms you find, and are great for keeping a record of what you've found.

What should you do if you want to find insects now? Well, the winter stoneflies should be coming out pretty soon...

1 comment:

  1. Informative post. Thank you so much for sharing the same. Keep blogging.