Tuesday, June 29, 2010

Bittacus chlorostigma

Hanging flies are unusual insects that often get overlooked. They aren't really flies at all. In fact they don't even look like flies. They are about an inch long and thin, and look a bit like large crane flies but they have four very obvious wings. Flies, of course (including crane flies), only have two wings.

Hanging flies are members of the Mecoptera, an order of insects commonly known as scorpion flies. This name is derived from certain species (in the genus Panorpa) where the males bear what looks like a stinger at the end of the abdomen. Hanging flies, however, do not have this threatening terminus and very often go undetected by even well-informed naturalists. This is unfortunate. They are fascinating insects to watch.

One easy way to tell them apart from crane flies or even damsel flies is to look at the head. Hanging flies (like most other mecopterans) have a pointed head. This picture is of Bittacus chlorostigma that I took earlier this year (in April) along the Merced River in California. It is a fairly common insect (if you know what to look for) in the spring throughout the open oak woodlands of the Sierra Nevada foothills. I have found them most commonly when the California poppies are in full bloom. This particular individual was out when a redbud was flowering a few feet away. The yellow spots (stigmata) at the end of the wings are very diagnostic, even if you can't get a good look at the head.

Hanging flies are best known for their unusual mating ritual where the males capture a prey item (usually a fly or small moth), hang from a small branch (or long blade of grass) with their forelegs, and then release a pheromone that attracts females. This is unusual among insects that use pheromones in that it is the male and not the female that sends the signal. Once a female finds the gift and accepts it, the insects couple. If the gift is too small the female looks elsewhere.

Most of the research that has been done on this interesting behavior comes from the Eastern and Midwestern species of Bittacus. The common California species (B. chlorostigma) is largely un-represented in these kinds of studies. A paper published in 1977 suggested that it was a nocturnal species because so little was known about it. This is certainly not true. I saw a pair exchanging gifts in April of last year above Pine Flat Reservoir. It was mid-morning and the pair was very approachable (unfortunately, I didn't have a good camera with me at the time). Some enterprising student might take this species on as a research project. They shouldn't be hard to find and they are quite attractive.

Thursday, June 10, 2010

Hoplia Beetles

There's a reddish brown beetle about the size of a large lady bug that you may have noticed on your roses or other flowers in the spring. Here in the Central Valley it shows up toward the end of April or the beginning of May and enjoys resting on velvety petals. If there are a lot of them, the flowers will end up with large areas of feeding damage, but this usually isn't the case. These insects only come out for a single generation a year and their first thought has nothing to do with eating, they are looking for mates.

These interesting insects are called Hoplia beetles. Their name is italicized because it is a generic Latin name – no American species in the genus Hoplia have common names. We have several species in the US and all of them can be recognized by the single large claw at the end of their hind legs. Other beetles have two claws (or occasionally none).

This is a picture of a mating pair of Hoplia dispar, on a blackberry blossom. It’s a common species in California. It is different from other Hoplia species in the shape of the fine white ornamental scales, which are strongly elliptical to almost round. Most other species have more elongate scales or no scales at all.

This side image of also of H. dispar. If you look closely, you can see that some of the scales are partially blue. This is an unusual color for insects but for some reason Hoplia beetles are sometimes colored this way. One very striking beetle is Hoplia caerulea from Spain that has its entire body covered with these pale blue scales (it’s worth doing an image search to see). It looks like a morpho butterfly version of a scarab.

So don’t be too alarmed if you find these beetles on your house plants. You can pick them off by hand and dispose of them if they become a problem. They do have the general appearance of Japanese beetles (though less colorful) but don’t do nearly the damage. One species (Hoplia philanthus) from Europe is known to be a pest in turf and pastures and may require a more aggressive control program. Here in the US, however, our species are much less of a problem.

This last image is Hoplia mucorea which is common in the mid-Atlantic states in the spring. It is less common than H. dispar but can be found in forested areas just as the leaves are starting to break out – around the time of the dogwood blooms. Watch for a small insect flying a foot or two above the forest floor. If you’re jogging or walking fast, you may miss them. They have a ponderous flight pattern because they only use one pair of wings to fly. The other wings (actually the forewings) are only wing covers (called elytra) and are held upright and out of the way of the flying wings. This makes for a slower flight, and in fact, you can often catch up with them and grab them with your hand. Don’t worry, they don’t bite. The worst the will do is give you a stout tickle you as they try and burrow between your fingers. Take a close look, they’re quite interesting and they’re out because it’s spring.