Insecta, Homoptera, Callaphididae .
Description, Biology, Life Cycle, Damage, Common Names, Images
It lives on the underside of the leaves of walnut, mainly on the terminal leaflet, usually along the veins. The fundatrix hatches from the winter eggs during April and the first days of May, and feeds on the buds or the young foliage.
The first generation and its descendants throughout the spring and summer are all alate parthenogenetic viviparous females until the time for sexual reproduction comes (in all usually 8-11 generations). These alate females are able to spares infestations. The sexual forms occur from September to November. The eggs are laid on the bark of stems, the base of buds or on the leaf scars.
The species overwinters as eggs.
Ants are not attracted by this aphid.
Large populations of the aphid on walnuts can reduce nut quality and yield although the leaves do not appear to react to the insect sucking. The sooty mould fungi supported by the honeydew excreted by the aphids reduce with the vigour of trees.
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.