Friday, August 17, 2007

Swamp Parasites

Today's topic became clear as the staff dashed once again from the parking area to the nature center in order to minimize their exposure to the biting flies that have persisted well beyond their anticipated departure date.

The flies (deer, horse, and yellow) are from the family Tabanidae. The males are easily identified because their eyes are connected while the eyes of the females are widely separated. However, after smashing the fly between the palm and scalp in response to a painful bite, it is difficult to ascertain if the eyes were originally connected. It will undoubtedly be a female, because as with mosiquotes, it is only the females that bite humans and other animals.

The flies are ambush predators. They lie in wait in shady area until they perceive a meal passing by. Darker clothing in motion appears to be the most attractive to the flies. Using their scissor-like mandibles, they can inflict a wound deep enough to cause bleeding. They also add an anti-coagulant to keep the blood flowing. A group of 20-30 flies feeding on a cow for six hours can remove 100 cc of blood! Beef cattle can lose substantial weight and dairy cattle milk production can be dimished. Audubon staff members can receive concusions when swatting at their tormentors while carrying briefcases or coffee mugs! DEET is an effective repellent as is the personalized fly trap. Don't wear this on a first date.

Other swamp parasites include the mosquito and a leech specializing in turtles (see images).

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