I’ve been hoarding these photos for a little while; I haven’t actually seen a mantis for perhaps a week or two, though there was a period in August and September when they were relatively abundant, like the grasshoppers. After I’d been observing them for a little while, I finally got around to getting some photos of them. But then the photos sat on my hard drive for some time longer, as I posted about other things, or didn’t post at all when I planned to. I find life has an unfortunately habit of distracting me from the blog. I suppose, on the flip side, the blog has a habit of distracting me from the rest of life, too, so perhaps it all balances out.
I almost never find mantises just sitting; usually when I spot them it’s because I’ve disturbed them from the grass and they go fluttering off to another spot some distance down the trail. You can always tell when it’s a mantis flying away from you – they have thin, delicate wings, long and rounded, that catch the light just so as they fly. They look like fairies, long slender bodies hanging between shimmering gossamer wings. I wouldn’t be the least bit surprised if the legends of fairies were begun by people seeing mantises flying away from them.
I took photos of two individuals. In both cases I watched them fly away and noted where they came to rest again. By carefully sneaking up on the spot I was able to locate them among the grasses and godenrods before they flew again. Although there are about 20 native species of mantis in North America, the most common species, at least in areas I’ve been, is introduced. It’s the European Mantis, Mantis religiosa, native to the Mediterranean and adjoining parts of Asia. I’ve seen different stories for the explantion: one that suggests it arrived accidentally on a shipment of plants, another that claims it was introduced as biological control. Ironically, it’s the official state insect of Connecticut. It can be told from our native species by the presence of black-and-white “eye spots” on the inner surface of the upper foreleg. There are two colour variations, a green and a brown. Just by fortunate chance, I happened across one of each colour morph.
The mantis’ claim to fame is really in its forelegs. These appendages not only give it its common name (“praying mantis”) for the activity called to mind when the insect is at rest, but are also deadly tools for catching and killing prey. The secret is in those sharp, curved talons that protrude from halfway down the foreleg. The mantis’ foreleg looks like it stops at the claw and the thin part beyond resembles a long pinky finger being held delicately aloft. Really, though, the thin part is the normal foreleg, and it’s just the upper part of the leg that has been modified. The mantis still walks on the long thin part of the leg (see above photos). Many insects have hair-like protrusions from their joints, and I presume the spur of the mantis is a modified one of these. As I’m sure you can guess, the claw is used for spearing prey, and for hooking and dragging prey back to the body. Mantises are strong – they can spear a hummingbird with those sharp claws and hold it, suspended, while they eat.
Unless the prey is very large, though, it isn’t the spur that holds them after capture. Rather, it’s the series of sharp spines that line the inside of the mantis’ leg. You can see the long spines along the middle segment and the shorter tooth-like jags on the fore-segment in the previous photo. When the mantis folds its leg, the prey is pressed into the “teeth” and held there. In doing some searching round the ‘net for mantis info, I found this photo at the arboretum of my old alma mater that shows a mantis holding a grasshopper. The “pinky finger” folds up out of the way while the claw is in use.
Praying mantises have huge eyes for the size of their head. Just like dragonflies or other predatory insects, mantids are strongly dependent on their vision for detecting and capturing prey. I’m not sure whether there’s a purpose to the stripes that cross through the eyes or not; they may simply be a form of camouflage, to break up the insect’s outline. Mantises are leaf/twig mimics, their shape and posture blending them in with their substrate both in order to hide from predators and to fool potential prey.
As vertebrates ourselves, and mostly used to seeing other vertebrates up close, we tend to think of mouths as being two-jawed – an upper and a lower. Insects, however, usually have three: one upper jaw or lip (called the labrum), and then two lower jaws (called the mandibles) that can open and separate to the sides. In addition to these, insects have a second set of separable appendages near their mouth, called maxillae, which function much like vertebrates might use a tongue, to manipulate food items. And underneath all this is the floor of the mouth, the labium, which basically just prevents the foot from falling out.
My interpretation of the mantis’ mouth here is that there is one tooth-like protrusion coming up from the bottom which is the labium; a thicker, darker red bit just above which is the mandible; a thin, multi-segmented appendage that is the maxilla; and then the nose that you can’t really see the end of, which is the labrum.
And no, I don’t think you can tell the sex of the mantis by whether or not it’s wearing lipstick.
Mantises are known for their reputation of “sexual cannibalism”, but the validity of this behaviour is debated. It’s been observed, sure – but mostly in the laboratory. Some argue that because mantises are highly visual insects, their behaviour is affected by the presence of people, and that cannibalism may be the result of distracted males, irritated females, or some other human-created cause. It’s rarely observed in the field, but it’s hard to say how much of that is because it doesn’t normally occur and how much is simply that it’s rarely observed. If the behaviour is accepted as valid and normal, then the next question is why does it occur. The leading argument there is that it lends a selective advantage to the male to be eaten because males whose heads have been removed end up copulating longer, and have a higher rate of fertilization, than those that are not cannibalized. Also, by eating the male the female may boost her metabolism and nutrients, leading to more and healthier eggs.
After mating, the female will find a sheltered nook in which to lay her eggs. When freshly laid, the eggs are in a soft, frothy cocoon that gradually hardens into what looks a little like a tiny pouch with a zipper up the middle. I found some last spring, and posted a photo of one here. They eggs overwinter in these, and hatch out in the spring. The young mantises spend the summer growing up before mating in the fall. If you happen to find an egg case, you can bring it in and overwinter it in a dry spot at the back of your fridge, much as you might do with a caterpillar cocoon. Bring it out and set it up in a terrarium in the spring, and watch the babies hatch and grow. Or, if you haven’t stumbled across an egg case you could collect, you can order your own mantis-raising kit from Discover Channel’s online store.