Table of Contents
Introduction
- What Hoverflies Are
- How to Identify a Hoverfly
- The Hoverfly Life Cycle
- How Hoverfly Larvae Control Aphids
- Hoverflies as Pollinators
- How to Attract Hoverflies to the Garden
- Pesticides and Other Threats
Conclusion
Introduction
Hoverflies are among the most useful insects found in gardens, orchards, and crop fields. Adults visit flowers and transfer pollen, while the larvae of many species prey on aphids and other soft-bodied pests. Hoverflies are also called flower flies or syrphid flies because they belong to the family Syrphidae. Many have yellow, orange, or white markings that make them resemble bees or wasps, but hoverflies cannot sting. Their mimicry may discourage predators, while their ability to stop and remain suspended in the air makes them easy to recognize. More than 6,000 hoverfly species have been described worldwide, but their feeding habits vary. Not every hoverfly larva hunts pests; some live in water, decaying organic matter, plant tissue, tree sap, or insect nests. The species most valued in gardens belong to groups whose larvae consume aphids, mealybugs, psyllids, scales, whiteflies, and other small insects.[1][2]
1. What Hoverflies Are
Hoverflies are true flies in the insect order Diptera. Like other flies, they have one functional pair of wings. Bees and wasps have two pairs. Hoverflies also have short antennae, large eyes, and no stinger. Many species copy the colors and body patterns of bees or wasps, but the resemblance is defensive rather than evidence that they are dangerous. Adults feed on nectar, pollen, honeydew, and water. Pollen provides protein needed for egg production, while nectar provides energy for flight. Their ability to move forward, backward, sideways, and remain nearly motionless above a flower separates them from most bees. Hoverflies occur in farms, gardens, forests, wetlands, grasslands, and cities wherever suitable flowers and larval habitat exist.[1][3]
2. How to Identify a Hoverfly
A hovering insect with black and yellow markings is often assumed to be a bee or yellowjacket, but several features identify a hoverfly. It has one visible pair of wings, short antennae, and eyes that often cover much of the head. It does not carry packed pollen on its hind legs or beneath its abdomen in the manner of many bees. Its abdomen may be narrow, broad, striped, spotted, or almost black, depending on the species. A hoverfly may approach a person to investigate sweat or moisture, but it cannot sting or bite. Adults often land on flat or open flowers where nectar and pollen are easy to reach. The USDA notes that flower flies can be important pollinators despite lacking the structures female bees use to carry concentrated pollen loads.[3]
3. The Hoverfly Life Cycle
Hoverflies develop through four stages: egg, larva, pupa, and adult. Females of aphid-eating species search plants for colonies of suitable prey and usually place their eggs near the infestation. After hatching, the legless larvae crawl among leaves and stems and begin feeding. Their bodies may be green, cream, brown, or partly transparent, which makes them difficult to see. After completing several larval stages, they form hardened oval cases called puparia, often attached to vegetation near the feeding site. Adults later emerge and return to flowers. The length of each stage depends on species, temperature, food, and season, so one fixed timetable does not apply to all hoverflies. Some species produce several generations each year, while others complete one generation or overwinter as larvae or pupae.[1]
4. How Hoverfly Larvae Control Aphids
The larvae of predatory hoverfly species are effective aphid hunters. They move across leaves, seize aphids with hooked mouthparts, and consume their body fluids. UC Integrated Pest Management reports that one aphid-feeding syrphid larva may consume about 100 to 400 aphids before pupating, depending on the relative sizes of the predator and its prey. Some species also eat mealybugs, whiteflies, psyllids, scales, mites, and small caterpillars. Their presence can reduce pest pressure without pesticide treatment, although they may not eliminate every aphid. Ants can interfere because many ant species protect honeydew-producing aphids from predators. Controlling ants and allowing small aphid populations to remain for a time can help hoverflies establish and reproduce. Research has also confirmed aphid DNA inside hoverfly larvae collected from commercial strawberry fields, supporting their role as natural enemies in crop production.[1][4]
5. Hoverflies as Pollinators
Adult hoverflies are frequent flower visitors and contribute to pollination in wild plants and crops. They pick up loose pollen on their bodies as they feed and carry some of it to other flowers. Their importance varies with the hoverfly species, plant species, weather, landscape, and availability of other pollinators. Hoverflies often use open flowers with accessible pollen and nectar, including plants in the carrot, daisy, mustard, and rose families. They should not be described as replacements for bees because their effectiveness differs among crops, but they expand the number and variety of insects moving pollen through a garden. Their dual role is important: adults use flowers, while the larvae of many species suppress pests living on the same plants.[1][3]
6. How to Attract Hoverflies to the Garden
A garden that supplies flowers across the growing season is more likely to support adult hoverflies. Suitable choices include alyssum, buckwheat, coriander, dill, fennel, yarrow, asters, goldenrod, and other plants with exposed nectar and pollen. Plant selection should match the local climate and should avoid species considered invasive in the region. Allowing some herbs and vegetables to flower can also provide forage. Small areas of shelter, leaf litter, decaying wood, damp soil, or clean water may support species whose larvae do not prey on aphids. A diverse garden is therefore more useful than one designed only for a single hoverfly type. UC IPM recommends flowering insectary plants because nectar and pollen can increase the abundance, longevity, and reproduction of syrphids and other beneficial insects.[1][5]
7. Pesticides and Other Threats
Broad-spectrum insecticides can kill hoverfly larvae along with the aphids they are intended to control. They may also kill adults visiting treated flowers. Before spraying, inspect aphid colonies for pale, tapered larvae or oval puparia. A strong stream of water, selective pruning, ant control, or time for predators to respond may reduce the need for pesticides. When treatment is necessary, use the least disruptive method permitted for the plant and pest, follow the label, and avoid treating open flowers when pollinators are present. Systemic insecticides can also expose beneficial insects through contaminated nectar, pollen, prey, or plant fluids. Preserving hoverflies requires tolerating some prey because predatory larvae cannot remain in a garden where every aphid is removed at once.[5][6]
Conclusion
Hoverflies combine two services that gardeners often seek separately. Adults visit flowers and contribute to pollination, while the larvae of many species consume aphids and other soft-bodied pests. Their bee-like markings protect them from some predators, but hoverflies have no sting and pose no threat to people. A garden with flowers from spring through fall, limited pesticide use, controlled ant populations, and a range of habitats can support more hoverflies. Their presence does not guarantee complete pest control, and not every species has predatory larvae. Even so, aphid-eating hoverflies are important natural enemies, and adult hoverflies add another group of pollinators to the garden.
Related Beekeeping and Pollinator Guides
Beekeeping the Right Way for Pollination and Colony Stability
https://hatchiseeds.com/pillar-beekeeping-the-right-way/
Large Beekeeping Systems: Stability and Performance Optimization of Colonies
https://hatchiseeds.com/large-beekeeping-systems-pillar/
Advanced Beekeeping: Productivity and Colony Health
https://hatchiseeds.com/bee-colony-health/
Insects and Pollinators — USDA Natural Resources Conservation Service
https://www.nrcs.usda.gov/conservation-basics/animals/insects-pollinators
References
[1] Syrphids: Flower Flies or Hover Flies — University of California Statewide Integrated Pest Management Program
https://ipm.ucanr.edu/natural-enemies/syrphids/
[2] Trophic Variety and Abundance of Hoverflies in an English Suburban Garden — Ecology of Freshwater Fish archive
https://pmc.ncbi.nlm.nih.gov/articles/PMC7163471/
[3] Is It or Isn’t It a Bee? — USDA Agricultural Research Service
https://www.ars.usda.gov/pacific-west-area/logan-ut/pollinating-insect-biology-management-systematics-research/docs/is-it-or-isnt-it-a-bee/
[4] Detection Rates of Aphid DNA in the Guts of Larval Hoverflies — Bulletin of Entomological Research
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/0C8B58208E0625413664C8EAB37F9166/S0007485321001115a.pdf/
[5] Beneficial Predators — University of California Statewide Integrated Pest Management Program
https://ipm.ucanr.edu/home-and-landscape/beneficial-predators/
[6] Aphids: Management and Natural Enemies — University of California Statewide Integrated Pest Management Program
https://ipm.ucanr.edu/home-and-landscape/aphids/