BY ALPER ÖZKAN (MSN/PhD)
d_ozkan@ug.bilkent.edu.tr
Last Monday, on my way back from a day’s work at UNAM, I had the good fortune to come across a Calosoma larva—also called caterpillar hunters, these beautifully colored beetles are voracious hunters both as larvae and adults, eating hundreds of caterpillars during their lifetime and even climbing trees to seek out their prey. I usually carry a vial on my person for these occasions, and the little insect, battered by wind and rain, needed no coercing to seek shelter in it—it now resides under my desk, buried in soil and awaiting some fresh caterpillars to feast on. It’s always a hassle to keep specialized predators, but I’ve read that they also do well on freshly crushed crickets, so I’ll see if I can handle the feeding—I’m trying to find a provider for either crickets or waxworms, as pet stores in Ankara evidently don’t stock live feed. But in any case, this week’s column will be on beetles, in honor of the latest addition to the ever-growing collection of bugs on UNAM’s fourth floor.
Lovecraft has written about a coleopterous race that will inherit the earth long after mankind’s demise, but the truth of the matter is that beetles need not wait for us to go—with over 350,000 described species occupying just about every ecological niche imaginable, the order Coleoptera already rules this planet. Their success, spurred by multiple factors in their evolutionary history (such as low rates of extinction and a rapid switch to feeding on flowering plants, which are also ridiculously speciose), is evident in the sheer diversity they exhibit: weevils, fireflies, scarabs, chafers, elaters, ladybugs, bombardiers, diving beetles, tiger beetles, stag beetles, leaf beetles, longhorn beetles and blister beetles all follow the same general body plan, but each type comes with unique twists that differentiate it from the rest of the stock.
Tiger beetles, for example, are characterized by their massive eyes, long legs and sharp, scything mandibles, which make them unmistakable for anything but sleek, cursorial predators—indeed, some tiger beetles can run at such speeds that they’re unable to see where they’re going, because they’re too fast for enough photons to hit their eyes and form a visual image (they compensate by taking short stops to reorient their vision and using their antennae as “seeing canes” while running). Ladybugs, in contrast, are predators of a different bent: they hunt soft-bodied insects and especially aphids, which do not need to be chased down but may be attended by ant bodyguards—and so ladybugs are thickly armored and equipped with foul-tasting blood (that some species can eject at will), protecting them from ants and birds alike.
Fireflies are also foul-tasting (which is why they can brazenly shine in the midst of darkness, making themselves completely obvious in the process and thereby warning potential predators in addition to attracting mates) and also predatory, but feed mostly on slow-moving prey such as slugs and snails by following the chemical signals found in their trails. Female Photuris fireflies, however, are an exception: they instead use aggressive mimicry to secure easy meals, imitating the flash patterns of other fireflies to attract males that are swiftly devoured. Interestingly, male Photuris will also emit signals matching other species, but for a wholly different reason: sometimes, a prey-seeking female will try to lure such a male and get a mate instead of a meal…or both, since they aren’t particularly averse to cannibalism either.
Herbivorous coleopterans, in contrast, are exemplified by weevils and leaf beetles—the boll weevil and Colorado potato beetle in particular are infamous for devastating cotton and potato crops worldwide, while jewel beetles and long-horned beetles (and especially the starry sky beetle) are major pests of trees. But weevils can also get into the deforestation business, and their take on it is exceptional: instead of consuming the wood itself, wood-boring weevils (which are called ambrosia beetles) bring with them a symbiotic fungus that grows on the galleries they excavate, nourishing them and slowly destroying the wood from within (fortunately, they tend to attack dead trees, though that doesn’t exactly endear them to the timber industry). Leaf beetles, for their part, are famous for the elegantly disgusting fecal shields of their larvae, which are accumulated in peacock-like “tails” behind the animals and serve to make them a thoroughly unattractive meal for anything with taste buds.
There is, of course, a lot more to say about beetles, as evidenced by the fact that this column is now registering at eight hundred words despite saying little more than “beetles exist” (well, it hasn’t even mentioned all the beetles, so let’s make that “some beetles exist”). But I’ll stop here for now, and end the column by noting, for these wondering about the ant colony, that the queen is healthy but reluctant to lay new eggs—I’ve given her some honey, and the protein from crushed crickets should help with the egg issue as well. Let’s see what comes out of her, the Calosoma and the apple snail eggs as well—I just got a new clutch, and they’re due to hatch soon.