Hoverflies are the world’s second most important group of pollinators after bees. With roughly 6,200 species found on every continent except Antarctica, these small flies visit flowers to feed on nectar and pollen, transferring pollen between plants in the process. Their contribution to pollination has been valued at an estimated $300 billion per year globally.
How Hoverflies Pollinate
Adult hoverflies feed almost exclusively on nectar and pollen. As they land on flowers and crawl across the reproductive parts to eat, pollen grains stick to their bodies and get carried to the next flower they visit. Their pollination style is less targeted than a honeybee’s, but it works. Individual hoverflies often show short-term loyalty to one flower species during a foraging trip, meaning they move pollen efficiently between plants of the same type rather than scattering it randomly across different species.
They tend to prefer open, bowl-shaped flowers where pollen and nectar are easy to access. Some species have longer mouthparts that let them reach into deeper flowers as well. Yellow and white flowers attract the most visits overall: roughly 38% of hoverfly visits go to yellow flowers and 31% to white ones, with purple flowers receiving about 26% and blue flowers only 5%.
Crops That Depend on Hoverflies
Hoverflies contribute to the pollination of a wide range of food crops. Their effectiveness has been specifically documented in watermelon (a crop that depends 90 to 100% on insect pollination for fruit set), mango, celery, and fennel. In greenhouse settings, where honeybee colonies can be difficult to manage, hoverflies are increasingly used as managed pollinators. More than 1,500 crops worldwide rely on insect pollination, and hoverflies handle a meaningful share of that work.
How They Compare to Bees
Bees are more efficient pollinators per visit because their fuzzy bodies pick up more pollen and they tend to be more methodical in working flowers. But hoverflies compensate through sheer numbers and by filling ecological gaps that bees leave open.
One key advantage is altitude. At higher elevations, pollinator communities shift from bee-dominated to fly-dominated. Hoverflies handle the cooler, windier conditions of mountain environments better than most bees. One common species begins moving at air temperatures around 11°C and actively feeds and flies between flowers at 13°C to 21°C. In mountain meadows, seed set for certain wildflowers increases with hoverfly abundance rather than bee abundance, showing that hoverflies can be the primary pollinator in the right conditions.
Hoverflies are also smaller-bodied than bumblebees, which means they overheat and dehydrate more quickly in extreme warmth. This makes high-altitude and cooler-climate environments a sweet spot for them: warm enough to be active, but not so hot that they burn through energy reserves.
Long-Distance Pollen Transport
Some hoverfly species are migratory, traveling hundreds of kilometers in seasonal movements. Researchers studying hoverflies that landed on a remote oil rig in the North Sea found that the insects had traveled over 500 km from the Netherlands, northern Germany, and Denmark, carrying pollen from dozens of plant species. After resting, these hoverflies likely continued another 250 km or more to Norway or the Shetland Islands. This long-range movement means hoverflies can connect plant populations across vast distances, potentially enabling gene flow between ecosystems that no local pollinator could link.
The Bonus: Pest Control
Hoverflies offer something no bee can: biological pest control. While adult hoverflies pollinate flowers, their larvae are voracious predators of aphids and other soft-bodied pests. A single hoverfly larva can consume up to 400 aphids during its development. When larval populations are high, they can reduce aphid numbers by 70 to 100%. This dual role, pollination from the adults and pest control from the larvae, makes hoverflies uniquely valuable in both gardens and commercial agriculture.
Population Declines
Hoverfly populations are under pressure. A long-term study in a Dutch forest tracked hoverfly numbers over four decades and found that overall abundance dropped by 80% between 1982 and 2021. Species richness fell by 44% over 43 years, with the characteristic dry-forest hoverfly community essentially disappearing. The earliest declines hit rare species hardest and coincided with intense nitrogen pollution and soil acidification from nearby agriculture. A second wave of decline beginning around 2000 struck even the most common species.
The likely drivers are regional rather than local: pesticide drift from agricultural areas, continued nutrient pollution, and climate change. Broader surveys across Britain found that average hoverfly distribution shrank between 1986 and 2010, with rare species declining while a few common generalists expanded.
Attracting Hoverflies to Your Garden
If you want more hoverflies visiting your yard, plant flowers with open, flat, or bowl-shaped blooms in yellow, white, and purple. Daisies, yarrow, fennel, sweet alyssum, and marigolds are reliable choices. Avoid double-petaled ornamental varieties where the pollen and nectar are buried or bred out. Letting some herbs like dill, cilantro, and parsley bolt and flower provides exactly the small, open blooms hoverflies prefer.
Equally important is tolerating a few aphids. Female hoverflies seek out aphid colonies to lay their eggs nearby, ensuring their larvae have a food source. A garden sprayed clean of every pest is a garden with no reason for hoverflies to stay and reproduce. Leaving a patch of the garden a little wild, with some weeds and unharvested herbs, creates habitat for both the adults and their pest-eating larvae.