Bloatfly (Fallout 3)

The Bloatfly is a common mutated Capital Wasteland pest resembling an oversized blow-fly. While a reasonable source of experience for greenhorn explorers - due to the weakness of, and ease of avoiding, their attacks - bloatflies become little more than pests as the player gains experience.

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 prosecute an attack with relentless single-mindedness. When attacking, bloatflies will emit a high-pitched shrill or scream, although the size of the insect prevents it from making a particularly loud call. A wanderer more than a dozen feet away will likely not hear the fly's call before being stung. Individually, they cannot inflict much harm, but in packs, 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 reasonably common.

Combat with Bloatflies
Primarily a low-level encounter, bloatflies are the second weakest enemy encountered in the Wastelands (only the ubiquitous Radroach is weaker) and can generally be killed with only one or two shots from a firearm.

Killing a bloatfly is, compared to most wasteland animals, straightforward and safe to all but the weakest wanderers. While it is possible to hit a bloatfly "on the wing" by live-firing a weapon, the animal's annoying tendency to jink and dodge makes targeting difficult. Using VATS with a low-use-cost weapon is the most efficient way to kill a bloatfly. Avoid using automatic weapons such as the 10mm SMG or Assault Rifle, as these weapons fire multiple rounds per trigger pull. Since a single round is typically adequate to kill a bloatfly, automatics waste at least two to four rounds of costly ammunition when engaging a bloatfly. Instead, use more basic weapons such as the 10mm Pistol or Hunting Rifle, both of which consume plentiful, inexpensive ammunition. Naturally, any single-shot weapon is more cost-effective in terms of ammunition expended, but using an overpowered weapon such as a Scoped .44 Magnum is a waste of expensive ammunition. Bloatflies, although weak to attack, are surprisingly durable: a rocket which can easily dismember a Raider will leave a bloatfly intact.

However, bloatflies are slow-moving for insects, and unless over-encumbered, can be avoided simply by fleeing on foot. While outdistancing a bloatfly does not take long, the animal can nevertheless strike several times before being put safely out of range. To that end, running in a zig-zag pattern to throw off the fly's aim is generally the most effective way to avoid being stung.