Hoverflies (family Syrphidae) are common insects often mistaken for stinging pests like wasps or bees due to their distinct black and yellow markings. These flies are harmless to humans and perform important functions in your garden and local ecosystem. If you are seeking to eliminate these striped insects, it is likely based on an incorrect identification or a misunderstanding of their nature. Recognizing these insects and their substantial benefits is important for maintaining a balanced environment.
Correct Identification: Hoverflies Versus Other Insects
To tell a hoverfly from a stinging insect, observe a few distinct physical and behavioral characteristics. The most reliable differentiator is the number of wings. Hoverflies, being true flies, possess only one pair of wings (two total), while wasps and bees have two pairs (four wings). Hoverflies also typically have very short, stubby antennae, which is a noticeable contrast to the longer, thinner antennae found on most bees and wasps.
Stinging insects, such as wasps, exhibit a narrow, defined waist connecting the thorax and abdomen, while a hoverfly has a wider, more rounded abdomen without this constricted segment. Their flight pattern is also unique; hoverflies are masters of aerial maneuverability, capable of remaining completely suspended in mid-air and darting suddenly in any direction. Despite their mimicry of stinging insects, hoverflies are completely incapable of stinging or biting humans.
The Importance of Hoverflies in the Ecosystem
Hoverflies indicate a healthy, functioning ecosystem due to their dual roles in pollination and pest control. Adult hoverflies primarily feed on nectar and pollen, making them significant secondary pollinators for a wide variety of plants. They contribute to the fertilization of many crops and garden flowers, often visiting flowers with easily accessible nectar.
The larval stage provides their most notable contribution to pest control. These legless, slug-like larvae are voracious predators of soft-bodied garden pests, primarily consuming large numbers of aphids, but also thrips, mealybugs, and scale insects. A single hoverfly larva can consume several hundred aphids over its two-week developmental period, effectively providing natural biological control. Eliminating the adult flies removes the next generation of these natural pest managers, potentially leading to increased aphid populations.
Managing Nuisance Hoverflies Without Harm
If hoverflies are becoming a nuisance, particularly by entering indoor spaces, non-lethal management strategies can reduce their presence. Exclusion is one of the most effective methods, involving fine-mesh screens on windows and doors to prevent them from entering the home. Since hoverflies are drawn to sources of nectar and decaying organic matter, maintaining cleanliness around entry points is helpful.
Removing attractants like fallen fruit or standing water in containers reduces the number of flies drawn to the area. For single flies that have accidentally flown inside, gentle relocation is the simplest solution. The cup-and-paper method allows for easy capture and release of the insect outdoors.
Strategic planting can offer a degree of deterrence if they are congregating in unwanted outdoor areas. While they are attracted to many flowers, plants like marigolds or mint sometimes have a mild repellent effect that can discourage them. If concentrated deterrence is needed, a mild, non-toxic spray made with water and dish soap can be applied to surfaces, but avoid spraying the insects directly.