Hoverflies (family Syrphidae) are among the most important and underappreciated insects in British gardens. Often mistaken for bees or wasps due to their yellow-and-black colouring, hoverflies are actually true flies — harmless, stingless, and incredibly beneficial. Their diet varies dramatically between life stages.
Adult Hoverfly Diet
Adult hoverflies are nectar and pollen feeders. They visit a wide range of flowers, using their sponging mouthparts to lap up sugary nectar and consume protein-rich pollen. This makes them important pollinators — second only to bees in pollination significance in many temperate ecosystems.
Adults show preferences for open, flat-topped flowers where nectar is easily accessible:
- Umbellifers (hogweed, cow parsley, fennel, dill)
- Daisies and asters (fleabane, ox-eye daisy)
- Buttercups and dandelions
- Lavender and marjoram
- Ivy flowers (critical autumn food source)
Hoverfly Larvae: The Aphid Destroyers
While adult hoverflies are peaceful flower visitors, many hoverfly larvae are voracious predators of aphids. The larvae of common garden species such as Episyrphus balteatus (the marmalade hoverfly) are slug-like, legless grubs that hunt aphids on plant stems and leaves.
Hoverfly Larva vs Aphids
- Daily consumption: A single larva can eat 30–50 aphids per day
- Lifetime consumption: Up to 400 aphids before pupation
- Hunting method: Larvae grasp aphids with their mouth hooks and suck them dry
- Active period: Larvae are most active at night
Not All Hoverfly Larvae Eat Aphids
The Syrphidae family contains around 280 UK species, and larval diets are surprisingly diverse:
| Larval Type | Diet | Example Species |
|---|---|---|
| Predatory | Aphids, thrips, small caterpillars | Marmalade hoverfly, Syrphus ribesii |
| Saprophagous | Decaying organic matter, stagnant water | Drone fly (Eristalis tenax) — “rat-tailed maggot” |
| Phytophagous | Plant bulbs and roots | Narcissus bulb fly (Merodon equestris) |
| Mycophagous | Fungi and decaying wood sap | Xylota species |
Did you know? The drone fly larva is called a “rat-tailed maggot” because it has a long breathing tube that extends to the water surface while the larva feeds on decaying matter at the bottom of stagnant pools. The adult drone fly is a convincing honeybee mimic.
Why Hoverflies Matter
Hoverflies provide a dual service: pollination as adults and pest control as larvae. Research published in the journal Ecological Entomology found that hoverflies can be responsible for up to 30% of pollination visits to crops in some systems. They are also important because many species are migratory — Episyrphus balteatus migrates from continental Europe to Britain each spring in huge numbers, supplementing resident populations.
Key Takeaway
Adult hoverflies eat nectar and pollen, making them valuable pollinators. Many hoverfly larvae are aggressive aphid predators, making them a gardener's best friend. By planting pollen-rich flowers — especially umbellifers — you can attract both the pollinating adults and their pest-controlling offspring.