Rat-Tailed Maggot

The rat-tailed maggot is the larval stage of the drone fly, a hoverfly that mimics a honeybee as an adult. The larva lives fully submerged in stagnant, often foul, oxygen-depleted water such as farm slurry pits, blocked drains, waterlogged compost, and shallow puddles heavy with decaying organic matter, an environment most other aquatic insects avoid.

Its most distinctive feature is a long, thin, retractable breathing tube extending from the rear of the body that acts like a snorkel, allowing the larva to remain submerged while feeding while still drawing air from the surface above. This tube can telescope in length depending on how deep the larva sits in the water, giving the maggot its rat-tail-like appearance and its common name. The species has a nearly worldwide distribution due to its association with human and agricultural waste habitats.

• Soft, cylindrical, grayish-brown to tan maggot-like larva, typically 12-20 mm long excluding the breathing tube
• A long, thin, telescoping tail-like breathing siphon extending from the rear of the body, which can stretch several times the length of the body
• Lacks a distinct head capsule, typical of fly larvae, with small hooked mouthparts used for filtering organic debris
• Found submerged in stagnant, nutrient-rich water rather than clean streams or ponds
• Adult drone flies are robust, honeybee-mimicking hoverflies with large eyes and a single pair of wings, unlike true bees

Rat-tailed maggots live in still, stagnant, often polluted or nutrient-rich water low in oxygen, including manure liquid, sewage-affected pools, blocked or poorly draining ditches, and wet compost or silage. They are found nearly worldwide, thriving anywhere organic-rich standing water persists, especially around farms and disturbed habitats.

The larvae are detritus feeders, filtering bacteria, fungi, and decaying organic particles from the water and sediment around them, a diet well suited to the nutrient-rich, low-oxygen habitats they occupy. Their breathing tube allows them to stay submerged and feeding for extended periods while still accessing atmospheric air. Adult drone flies, by contrast, visit flowers to feed on nectar and pollen and are important pollinators, illustrating how dramatically the ecological role of this species shifts between larval and adult stages.

Adult female drone flies lay eggs directly on or near stagnant water rich in organic matter. The hatched larvae live and feed underwater for several weeks to months, extending their telescoping breathing tube to the surface as needed. When mature, the larva moves to drier ground near the water's edge to pupate within its own hardened, barrel-shaped larval skin. The adult drone fly emerges afterward, resembling a honeybee, and feeds on flowers before mating and laying eggs to start a new generation.