Syrphid Flies: "Have you Hugged a Flower Fly Today?"
By Judy Ferris, ACLT Guest Blogger
As springtime bursts into bloom, you may have noticed tiny bee-like insects hovering amongst your flowers. Many of these little insects wear convincing yellow and black bee costumes. You may wonder “What are they?” And more importantly “Do they sting?”
In fact, these gentle creatures are Syrphid Flies [pronounced SUR-fid, as in the Beach Boys’ smash hit “Syrphid USA”]. Also called Flower Flies. Their colors alone scream “I’m bad! Very bad!”. But their bee-like disguise is all a bluff. Flower flies have no stinger, no venom, and cannot bite. Any bird that has been stung by a wasp or a bee is likely to avoid repeating that mistake. Thus, the yellow and black warning colors of Flower Flies scare predators into leaving them alone. Flower flies, then, operate under the radar and get a free pass from many predators in your garden!
Adult Flower Flies range in size from 1/3 to 1 inch. They are often called Hover Flies for their ability to hover in place and even fly backwards! Both are rare skills in the insect world. Thus, hovering itself is a clue to Syrphid fly identification. Adult Syrphids feed on nectar for energy and pollen for protein. They are excellent pollinators; in some crops even out-performing bees! Their attention, however, is focused on mating and egg-laying. Female Flower Flies lay tiny, white, football-shaped eggs near thriving aphid colonies. (I can just hear you groaning “Oh no! Here we go again with those poor aphids!”) Some evidence suggests that female Flower Flies can actually dole out the proper amount of eggs proportionate to an aphid population. Just enough larvae will hatch to control the aphid outbreak. Wow! Flies that can do math!
Eggs hatch in about a week and the leech-like larvae set to work. Syrphid fly larvae are nocturnal predators of small insect pests. They snooze by day, then awaken after dark to wreak havoc on aphids, thrips, scales, and caterpillars of both butterflies and moths. Blind and legless, the larvae stumble in the darkness until they bump into something edible. The mouth of the larvae is equipped with an efficient hook, typical of many fly maggots, which is used to grab prey. The hapless victim is thus lifted overhead and held up off the surface as it is gulped from the hook.
According to Michael Raupp of the University of Maryland, a single Syrphid fly larvae can eat more than 25 aphids per day and an estimated 200 aphids in the course of their development. With a healthy balance of maggots and aphids, 75% to 100% of the aphids can be controlled. For a fascinating 2-minute video of a Flower Fly larva chowing down on aphids, click on the link below. Keep your eye on the lower left corner of the video for clueless aphids.
How do you get this aphid-chomping action in your garden? To attract Flower Flies, grow the plants they love! Composite blooms – Yarrow, Queen Anne’s Lace, cornflowers, parsley, carrots, coriander, dill, and fennel are Flower Fly favorites. Syrphids are particularly attracted to white and yellow flowers.
The fortuitous combination of pollinator and pest-remover make the gentle Flower Fly your ideal garden companion! Look for these small visitors where flowers bloom. With luck, you may spot more than one species of flower fly; each identifiable by its unique color pattern. It almost goes without saying; if you see aphids, skip the pesticides and allow Mother Nature to work her magic instead. And don’t forget to hug a Flower Fly today!
