Grapevine aphid, Aphis illinoisensis (Shimer)
This is taken primarily from an
extension bulletin by D. G. Pfeiffer & P. B. Schultz, entitled
"Major Insect and
Mite Pests of Grape in Virginia" (Va. Coop. Ext. Serv. 444-567 (1986))
The winter host of this aphid is Viburnum (black
haw). Winter is passed
in the egg stage, mainly around buds. Eggs hatch in early spring over a
2-3
week period. A few parthenogenetic (reproducing without males)
generations
occur before winged migrants leave for grapevines. Colonies of dark
brown
aphids develop on young shoots and leaves (Plate 16, Fig. 10). When
populations
are high some may feed on fruit clusters, causing some berries to drop.
In fall,
winged individuals are again produced; these return to viburnum and
produce
males and females. The sexes mate and overwintering eggs are produced.
This species is usually not important enough to necessitate specific
treatments.
Grapevines are of sufficient vigor to tolerate some attack and the
aphids are
subject to attack by predators (e.g., ladybird
beetle adults
and larvae, and lacewing larvae).
Dry weather is conducive to buildups of aphid populations.
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