Hoverfly
Syrphidae
Role in the garden
A dual role: ADULT = pollinator, a flower-visitor (nectar and pollen); LARVA = an aphid predator in nearly 250 species, each larva eating about 400 aphids in its lifetime (INRAE, Encyclop'Aphid). Wasp mimicry (but harmless, no sting).
Activity period
March to October
How to attract / manage it
The marmalade hoverfly (Episyrphus balteatus) is the most common in the vegetable garden. Recognisable by its hovering flight in front of flowers (“flies that hover in place”).
Practical guide
Sources
- Turpeau, E., Hullé, M. & Chaubet, B. : Diptera Syrphidae, Encyclop'Aphid (INRAE)
- RHS (Royal Horticultural Society) : Hoverflies (rhs.org.uk/biodiversity/hoverflies)
Favourite plants / resources
Related plant entries
Carrot
In the vegetable garden, the carrot is planned first and foremost around its pest, the carrot fly, hence the value of interplanting it with onions. Its taproot needs loose, deep, stone-free soil (RHS), without a heavy application of manure just before (GAB/FRAB Bretagne). And when left to flower, this umbellifer opens up umbels that feed hoverflies and other small beneficials, like the other Apiaceae so valued for drawing in pollinators and aphid predators.
Fennel
Reputed to hinder its neighbours (effect shown mostly in the laboratory): grow it apart as a precaution. But very useful to pollinators, and a host plant of the swallowtail.
Coriander (cilantro)
An annual umbellifer with white umbels, coriander is a valuable insectary plant for beneficial wildlife: its small, wide-open, easily accessible flowers feed bees, hoverflies and parasitoid micro-wasps (ichneumons); the larvae of the latter two keep aphids and caterpillars in check. Letting a few plants run up to flower, rather than harvesting everything for leaf, turns a row of coriander into a larder for these predators and parasitoids. Short-lived, it bolts quickly to seed in hot weather: it is best sown in succession and readily slipped between rows, as it tolerates partial shade. Traditionally grown alongside carrots and cabbages, it diversifies the scents of the bed and fills the space between slower crops.
Dill
A major apiaceae for attracting pollinators and helpers (hoverflies, ichneumons, lacewings) to its yellow-green summer umbels. To be let go to seed. Self-seeds faithfully. A classic companion of the cucumber, to be avoided in direct contact with the carrot, which mature dill tends to outcompete.