Syrphid flies are a common sight in gardens and fields, often mistaken for more formidable insects. Many wonder if these small, hovering creatures, frequently adorned with bold stripes, pose a threat to humans. This article explores the nature of syrphid flies, addressing whether they bite and highlighting their significant roles in various ecosystems.
Understanding Syrphid Flies
Syrphid flies, widely known as hoverflies or flower flies, are a diverse group of insects belonging to the family Syrphidae. Adult syrphid flies range from 1/8 to 1 inch (4 to 25 mm) and exhibit striking color patterns, usually black or brown with yellow, orange, or white bands or spots on their abdomens. Their large eyes and short antennae are distinguishing features. They are named “hoverflies” for their ability to remain suspended in mid-air and dart quickly.
They are found around flowers, where adults feed, and near soft-bodied pests, which provide food for their offspring. Unlike bees and wasps, syrphid flies possess only one pair of wings, a characteristic of all true flies. This, along with their hovering ability, differentiates them from stinging insects they often resemble.
Why Syrphid Flies Don’t Bite
Syrphid flies do not bite or sting humans. Adult flies possess spongy mouthparts, adapted for lapping liquids rather than piercing or biting. They use these mouthparts to consume nectar, pollen, honeydew, moisture, and salts from surfaces, including human skin.
Their resemblance to bees and wasps is a defense mechanism known as Batesian mimicry. This mimicry deters potential predators, such as birds or other insects, by appearing dangerous, even though they are harmless. Syrphid flies enhance this deception through behavioral mimicry, such as waving their legs or pretending to sting when threatened.
Their Beneficial Contributions
Beyond their harmless nature, syrphid flies play valuable ecological roles. Adult syrphid flies are important pollinators, visiting flowers to feed on nectar and pollen. While consuming these, they inadvertently transfer pollen, contributing to plant reproduction.
Syrphid fly larvae provide significant benefits, particularly in pest control. Syrphid larvae are voracious predators of soft-bodied insects, including aphids, thrips, mealybugs, and mites. A single larva can consume 100 to 600 aphids during its development, potentially reducing aphid populations by 70% to 100%. This predatory activity makes them valuable allies in gardens and agriculture, offering natural pest management.