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.

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