Bloatfly (Fallout 3)

A Bloatfly is a common mutated Capital Wasteland pest resembling an oversized blow-fly. While a reasonable source of experience for greenhorn explorers — due to their weakness and the ease of avoiding their attacks — Bloatflies become little more than pests for even novice players.

Behavior
A common encounter in the Wasteland, the comparatively diminutive Bloatfly is quite aggressive, often attacking animals much larger than itself with reckless abandon. Bloatflies do not attack at close range, but rather keep to a standoff distance and pepper their prey with spine bedecked larva launched from its abdomen. The supply of these larva is seemingly inexhaustible, and unless evaded or eliminated, Bloatflies will persecute an attacker with relentless single-mindedness. When attacking, Bloatflies emit a high-pitched cry. A wanderer more than a dozen feet away will likely not hear the fly's call before being attacked. Individually, they do not inflict much harm, but in swarms Bloatflies can be a serious nuisance to explorers and potentially deadly to weaker companions.

Bloatflies typically live in small groups of two to four individuals, although lone bloatflies are also common.