ABSTRACT
Petroleum is a mixture of hydrocarbon compounds, many of which are toxic or otherwise harmful to most living organisms. Near oil wells, it is not uncommon to see open pools of petroleum, beneath which rainwater collects. The stickiness of the petroleum almost immediately immobilizes insects and blocks their spiracles, causing a quick death. The lethal conditions for most insects in the petroleum pools makes it particularly surprising to encounter many small adult flies on the surface of the petroleum and to find the larvae of these flies in or beneath the sticky black mass of crude oils, water, and soil. The adults and larvae of petroleum flies have distinctly different habitats. The adaptation of the petroleum flies to life in the remains of crude oil that seeped through natural processes from the ground probably occurred during relatively recent times, on a geological scale.
