Another Termite Species In Fern Bluff

Another Termite Species (Amitermes spp.)
In Suburban Northwest Round Rock on 08-20-2000

Jerry Cates

I often find termites of the genus Reticulitermes in Fern Bluff, Stone Canyon and the Oaklands. Most of these are R. flavipes, a species of subterranean termite which is also known as the "Eastern sub." This happens to be the most common of the subterranean termites found in this region. The Eastern sub usually swarms in the early spring. On August 20, 2000, I found winged termites in one of my insect collection stations. The termites had evidently swarmed sometime in the late morning or early afternoon, because they were not in that station earlier in the morning.

Mature termite colonies produce swarmers. When conditions seem right, alates (winged kings and queens) emerge from the termite colony and fly away to found new termite communities. Certain species tend to swarm at specific times of the year, and the date of the swarm is one of many indications of the type of termite involved. Swarming habits, though, are thought to be linked to the weather, and weather conditions here this summer have been unusual. For that reason, atypical swarming behavior might also be expected.

Next I looked at the veins in the wings. Termites exhibit distinct wing vein structures that tell us a lot about them. The wings of this termite were remarkably plain, with very few veins. They had none of the conspicuous oblique cross-veins between the radial sector veins that are common with dry-wood termites, and the radial veins were only lightly pigmented. This suggested that they were members of the higher termites, or Termitidae.

The eyes helped narrow the identity of this termite down more precisely. Termite workers are generally blind, but reproductive forms, such as these alates, have not one but two forms of eyes: a compound eye on each side, and a simple eye or ocellus next to each compound eye..

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Termites are not strong fliers, and a given swarmer only flies once in its lifetime. Because of this, we can be fairly certain that the parent colony is not too far away from the location where the alates were found.

The bodies of these specimens were medium brown in color, with dark gray wings. The length of the bodies, from the head to the tips of the wings, was relatively small, between 9-10 mm. This suggested they were not Formosan Termites, whose bodies are usually 12-15 mm long. That was good news. Formosans, which are among the most destructive termites in the world, have already been found in Austin. although that is not their preferred habitat. Most of the Formosans found this far inland have been brought here in wood timbers, particularly in railroad ties used in landscaping.

Under the microscope the wings were partially pubescent, or hairy, but the hairs were confined to the edges of the wings and the costal veins. This was an important clue to their identity, and practically eliminated them from that group of termites that is most destructive of residential structures. Formosan termite alates have hairy wings, but the hairs cover most of the surfaces of the wings.

The head was then examined more closely. The jaws were not large, and did not extend beyond the head capsule, as would be expected if these were soldierless termites (Anoplotermes fumosus, which we often find in pastures between Round Rock and Georgetown). The presence of an obvious fontanelle, or glandular pore in the top of the termite's head, confirmed this. A. fumosus does not have a fontanelle. In the photograph, the fontanelle is the small, light-colored region in the upper left quadrant of the head capsule. The antennae were noted to have 15 segments.

The distance between the ocellus and the compound eye is distinctive for certain termite species. The compound eye in the photograph is the olive colored region in the lower right quadrant of the head capsule. The ocellus is the lighter colored elliptical object just above the compound eye. In this case the distance between the ocellus and the compound eye is about one-half the diameter of the ocellus. That, along with the other measurements and observations already noted, strongly suggested that this termite was of the genus Amitermes. At least 75 species are in this genus worldwide, and some eight species are found in the U.S., specifically in the desert southwest. They pose a relatively low hazard to residential structures.