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General
The strawberry aphid, Chaetosiphon fragaefolii, has a cosmopolitan distribution and is the most important aphid pest of strawberries. It can cause direct damage by feeding and transmits viruses.
Life cycle and appearance of Strawberry aphid
Aphids moult four times before reaching adulthood. With each moult they shed white skin, betraying their presence in the crop. Reproduction of the strawberry aphid is exclusively by parthenogenesis, with unfertilized viviparous females continuously producing new generations of females. The strawberry aphids overwinter as parthenogenetic forms. There is no sexual stage and no eggs are laid.
Adult wingless females of Chaetosiphon fragaefolii are translucent yellowish white to pale greenish yellow, with red eyes. The body is covered with conspicuous capitate hairs. They are relatively small aphids with a body length of only 0.9-1.1 mm.
The aphids mainly feed on the underside of young leaves. On outdoor strawberries, winged aphids appear in May and June; these aphids disperse to other plants and fields. Winged aphids appear again from October to December.
Damage symptoms
Chaetosiphon fragaefolii is one of the most serious pests affecting strawberry plants. Direct damage is caused by the aphids sucking sap from the plant, which reduces the yield and quality of fruit. The leaves do not become distorted but leaves and fruits quickly become sticky due to the honeydew the aphids excrete. Black sooty mould fungi grow on the honeydew. The strawberry aphid is an important vector of several plant viruses affecting strawberries.