Marin Rose Society

FAST FACTS - SYRPHID FLIES
by Nanette Londeree, Master Rosarian

SIGNS

Adult flying insects with black and yellow bands on their abdomen

Tiny whitish to gray oblong eggs, singly on their sides, usually near aphids or within aphid colonies

Legless larvae 1/32 to 1/2 inch long, with a yellow longitudinal stripe on the back

Pear-shaped, green to dark brown pupa found on plants or on the soil surface

SYMPTOMS

Honeybee looking insects hovering over flowers

CAUSE

Syrphid or hover flies in the Syrphidae family

1000 species in North America, many being very abundant

OPTIMAL CONDITIONS / HABITAT

Regularly found where aphids are present in agricultural, landscape, and garden habitats

Adults feast on pollen and nectar – favorites include wild carrot and mustard, coriander, dill, fennel, sweet alyssum and yarrow

Their movement from flower to flower makes them an important pollinator

Usually most visible in the latter half of the growing season, after aphid infestations have been well established

TREATMENT

Prevention:

None - these insects should be encouraged with diverse plantings of nectar and pollen producing plants

Elimination:

None - you don’t want to eliminate these from the garden

GOOD GUY / BAD GUY?

A really good guy; the larvae are predators and the adult is a pollinator

Syrphid Fly photo by Jill Fromer, used with permission from:
http://www.istockphoto.com/