Syrphid Flies: Colorful Beneficial Insects for Aphid Control

In a pesticide-free garden, many beneficial insects keep problem insects like aphids in balance. One of the most attractive and interesting is the syrphid fly.

Syrphid flies are colorful, charismatic, fun to watch, and easily supported with diverse flowering plants. Adults are good pollinators, visiting flowers for nectar and pollen. Turn over a leaf on an aphid-afflicted plant and you'll find syrphid larvae swinging heads side to side, catching and devouring aphids. What more could a gardener ask?

Latin name: Family Syrphidae, subfamily Syrphinae
Common names: Syrphid flies, flower flies, hoverflies
Common genera: Eupeodes, Chrysotoxum, Pipiza, Paragus, Toxomerus, Syrphus spp.
Distribution: Abundant, diverse, worldwide except arid regions.
Habitat: Adults attracted to any flower-rich habitat with adequate food.
When to look: Multiple overlapping generations per year; most active summer when prey active. Adults in spring; adults and larvae in summer and early fall.

Syrphidae is a large family including aphidophagous (aphid-eating) flies (subfamily Syrphinae). Many larvae in other subfamilies develop in aquatic environments; a few in ant nests. Most adults are flower visitors/pollinators, feeding on nectar and often pollen.

How They Help

Each year gardens provide changing displays. Certain plants get aphids; populations can threaten plant vitality. Before insecticides, check for syrphid larvae (and other beneficials) already reducing aphids. Learn to attract adult syrphids so they take up residence and help win the aphid war.

Gardening for syrphid flies is simple—follow four recommendations:

1. Plant a variety of open flower forms with accessible resources.
2. Ensure plants flower throughout the season (early spring to fall).
3. Do not use pesticides, especially insecticides, on flowering plants. Beneficials eliminated with pests; pests rebound faster.
4. Leave leaf litter and plant debris in perennial garden around flowering plants. Syrphids need protected overwintering places, usually under leaf litter.

How to Spot a Syrphid Fly

Adults:

Don't be fooled—many are convincing bee/wasp mimics. Striped/spotted patterns make them look menacing to predators. To distinguish: look at antennae length. Flies have short, stubby antennae; bees/wasps have longer, proportional antennae. Syrphids have large eyes encompassing more of head. Like all flies, they have two wings (one per side); bees/wasps have four (two per side, sometimes hooked together appearing as two). Adults are very good fliers—many hover and dart quickly.

Babies (larvae):

Look like caterpillars with elongated, legless bodies. Often distinctive coloration/markings; some smooth light green to translucent, others striped or spiny.

How to Lure Them

Syrphid adults are regular flower visitors, consuming nectar and pollen—effective pollinators. Females feed on pollen (protein for egg production), using sponge-like mouthparts, holding anthers with forelegs. A pesticide-free garden with diverse flowering plants throughout the season attracts many syrphid types.

Forage plants for adults:

Adults like open flower forms with easy-access resources: Asteraceae (aster), Ranunculaceae (buttercup), Apiaceae (parsley), Rosaceae (rose) families. Complex flowers with narrow corollas limit nectar access (syrphids have short tongues). Adults also feed on pollen from grasses and sedges, especially early spring when other forage limited.

Leaving leaf litter is crucial—many syrphids overwinter under it (as larvae, pupae, or adults).

Sample plant list for adults:

• Early spring: Virginia waterleaf (Hydrophyllum virginianum), marsh marigold (Caltha palustris), Sprengel's sedge (Carex sprengelii)
• Spring: Ohio spiderwort (Tradescantia ohiensis), cicely (Osmorhiza spp.), Canada anemone (Anemone canadensis), wild rose (Rosa blanda), Greek valerian (Polemonium reptans), Golden Alexanders (Zizia aurea), Beardtongue (Penstemon spp.)
• Summer: Black-eyed Susan (Rudbeckia hirta), great St. John's wort (Hypericum pyramidatum), false sunflower (Heliopsis helianthoides), prairie cinquefoil (Potentilla arguta), purple prairie clover (Dalea purpurea), blazingstar (Liatris spp.)
• Fall: Stiff goldenrod (Solidago rigida), zigzag goldenrod (Solidago flexicaulis), showy goldenrod (Solidago speciosa), asters (any species)

Prey for larvae:

Syrphid larvae are predaceous; diet primarily other insects: aphids, spider mites, insect eggs, thrips, scales, mealybugs. If insect prey unavailable, some Syrphinae larvae consume pollen.

Sample plant list for larvae: Any plant afflicted by aphids, e.g., Heliopsis spp., Silphium spp., milkweed (Asclepias incarnata).

Life Cycle

Complete metamorphosis: egg → three larval stages → puparium → adult. Females seek aphid populations, lay single eggs or clusters on leaf undersides near aphids. Eggs white/cream, elongated oval. Larvae hatch within 3 days, crawl to prey. Voracious predators, often attacking aphids larger than themselves. When ready to pupate, larvae attach to leaf or stem. Some overwinter as pupae in leaf litter until spring. Adults live 3–9 weeks.

Shown: Pipiza sp. feeding on pollen on wild geranium (Geranium maculatum) flower. Pipiza syrphids are specialists; larvae feed exclusively on gall-forming aphids.

Region by Region: What to Do in Your Garden This Month