Black Witches and Other Migratory Insects
Ro Wauer, August 24, 2003, The Victoria Advocate, © 2003
The recent abundance of black witches, probably due to their arrival with Hurricane Claudette, has attracted lots of attention. This huge, mostly all-black moth that hides in dark places during the daylight hours, cannot help but startle anyone confronted with its sudden departure from it's hiding place. At my house, the relatively dark front porch or open garage are favorite perching sites. Its great wingspan, as much as five to six inches, is more bat-like than moth-like. But if you approach one slowly without frightening it off, its very dark appearance features large eyespots on both the forewings and hindwings. It is a remarkable insect up-close.
These tropical moths tend to be crepuscular, flying primarily at dawn and dusk, but they also fly during the daytime in strongly shaded forest areas. They feed on rotting fruits, such as mangos and bananas. These fruits also provide excellent bait for anyone wanting to study them in the open. And as was mentioned in a nature note a couple weeks ago, Brush Freeman found that they also feed on beer.
The question, of course, is from where did these great moths come? Although Claudette more than likely carried them across the Gulf from Mexico's Yucatan Peninsula, that doesn't mean that the storm picked up a few hundred individuals and carried them to the Texas Coast. More than likely the storm encountered a mass of migrants somewhere along the way. And Claudette may also have carried numerous other insects along to deposit them in Texas.
There are many insects known for their migrations. One of the best known of these is the monarch, a large orange-brown butterfly with black veins. This butterfly passes through Texas in spring on its way north and again in fall, en route to its wintering ground in Mexico. But several additional butterflies also migrate, although they do not get the same kind of recognition. A few of the better known butterfly migrants include cloudless and lyside sulphurs, little yellow, sleepy orange, American snout, gulf fritillary, common buckeye, red admiral, painted lady, and queen. Three skippers - long-tailed and ocola skippers and Dorantes longtail - also migrate.
Other migrant moths include the pink-spotted hawkmoth, mournful and tersa sphinx, and several species that can cause considerable crop damage: black cutworm, cotton leafworm, velvetbean caterpillar, corn earworm, armyworm, beet and fall armyworm, and soybean and cabbage loopers. Most of these moths are known from their caterpillar stage, rather than the adult.
There also are a number of dragonflies that migrate. The common green darner is our best example, but the twelve-spotted and wandering gliders, variegated meadowhawk, and Carolina, black, and red saddlebags also migrate. All of these insects have been found far out in the Gulf, and at times they can appear at oil rigs in great numbers.
Grasshoppers comprise another group of insects known to migrate. Although a few species, such as migratory grasshopper and Rocky Mountain locust, are recognized as true migrants, most grasshoppers that suddenly appear en mass are not migrants. These bugs, that can suddenly appear in the thousands and commence to destroy crops, are most often the result of mass hatchings, following perfect weather conditions. They then fly up en masse and seek food, but they do not make annual north-south migrations.
Moths, butterflies, dragonflies, and grasshoppers are not the only Texas insects that migrate. It may be surprising to learn that numerous other species have also been documented as migrants. Some of the more obscure migrants include the large milkweed bug, three leafhoppers, greenbug, and the convergent ladybird beetle.
Fall is rapidly approaching, and we should begin to detect southbound monarchs any day. For many of us, migrating monarchs are not just migrating butterflies, but they seem like mystical creatures.