Gasterophilus

Gasterophilus is a genus of parasitic flies in the family Oestridae, more commonly known as botfly. Gasterophilus are nonpathogenic, and seldom cause disease unless large numbers of larvae are present. Gasterophilus are found worldwide, but are prominently present during the summer months. The eggs of bot flies are laid on the fur of the host and are either hatched spontaneously or are stimulated to hatch by a stimulation of increased moisture and warmth obtained form an animal that self-grooms. These eggs are laid on different portions of the body according to the various Gasterophilus species. Once the eggs are hatched the first and second stage of the larvae develop within the animal’s oral cavity until they are swallowed where they can mature into the third larvae stage within the stomach. The larvae then detach from the gastric mucosa within the stomach and are passed through the feces and pupate. Adult bot flies then emerge and the cycle repeats. There are six species of Gasterophilus: Gasterophilus are medium to large flies and are 10–20 mm (0.39–0.79 in) long. They look similar to drone bumble bees, with clear wings with brown patches, and produce creamy-white eggs, around 1–2 mm (0.039–0.079 in) in length. The adults have non-functional mouthparts, so they cannot feed. G. haemorrhoidalis and G. nasalis have two rows of spikes on the ventral surface of the larval segments. G. intestinalis has mouth parts that are not uniformly curved dorsally and the body spikes present have blunt-ended tips.  'Bots' . The American Cyclopædia. 1879.