Apple Aphid

Fruit IPM Fact Sheet

Apple Aphid

Scientific Name – Aphis pomi (De Geer)

Family – Aphidae

Reference: Common Tree Fruit Pests Angus Howitt, 1993,
NCR 63 - Michigan State University

The apple aphid is a European insect. It was first reported doing serious damage to young apple trees in the eastern United States in 1849.

Life Stages
Egg: The shiny black eggs vary in size but are generally about 0.50 mm long and 0.25 mm wide.

Apple aphid adults and nymphs Nymph: The nymphs are all viviparous wingless females. The five instars include the last stage, which is the stem mother.

Adults: The wingless viviparous females are pear-shaped and light green, though in spring, some may have bright yellow bodies. The females have peculiar sensory pits on their hind tibia and are about two-thirds as large as the parthenogenetic wingless summer forms. The yellowish brown males, which have blackish antennae longer then their bodies, are one-third smaller and much less numerous then the females. In contrast to the well developed cornicles of the rosy apple aphid, the cornicles of the apple aphid are scarcely developed. The rosy apple aphids has longer antennae then the apple aphid.

Host Range
The aphid is a pest of apple, pear, quince and hawthorn. It is generally distributed in the apple-growing areas of the United States and Canada.

Injury or Damage
The apple aphids is abundant during June and July on young trees, water sprouts and vigorously growing terminals. It curls the foliage and covers it with honeydew. Black fungus that grows on the honeydew smuts both the fruits and the leaves and causes considerable discoloration, especially of early apples.

Factors Affecting Abundance
Early-season abundance is stimulated by migration from trees that harbor large numbers of aphids. In addition, lack of pruning – which promotes water sprouts and fruit and foliage in dense shade – encourages rapid expansion of aphid colonies. Foliar senescence and predator activity are important factors in lowering aphid populations.

Life History
The wingless females lay eggs mostly on the bark or on the buds in the fall. The eggs hatch in the spring about the time the buds begin to open. The eggs hatch into stem mothers, which give birth to a generation of viviparous aphids, about three-quarters of which develop into winged females. The rest remain wingless. The winged forms spread the species other parts of the tree or to other trees. About half of the second generation and some of the later generations may develop wings and migrate. Unlike the rosy apple aphid, the apple aphid lives on the apple tree all year. It reproduces continuously during the summer. In August and during the autumn months, the species is found almost exclusively on water sprouts or terminals of young trees that are still growing. The male and female sexual forms are produced there. After mating, the female lays eggs.

This species usually appears somewhat later in the spring than the more common apple grain aphid and is not as numerous on the buds because it waits until the leaves unfold. Because it reproduces on the trees during the whole season, however, it may be more injurious then the rosy apple aphid. Its damage resembles that of the rosy apple aphid – the leaves often curl very badly. Apples dwarfed by aphids look puckered at the blossom end.

Monitoring
Beginning in early June, select 10 growing shoots (not spurs) on each of five trees in a block. If an average of more than four leaves on the shoots are infested with wingless aphids, an insecticide application is recommended. If predators are active, delay treatment and check their effectiveness one week later.

Control
Apply preblossom applications of contact or systemic aphicides. Apply foliage applications of systemic compounds in early season or summer. Early applications when the aphids are fully exposed and before they curl the leaves are most effective. Systemic pesticides are required when the leaves have curled.

If aphicides appear to be ineffective, it is possible that spirea aphids are present. Spirea aphids are more difficult to control than apple aphids. Recently it has been shown that, in some states – including Virginia, West Virginia, Pennsylvania, New York and possibly Ohio and Michigan – a substantial proportion of apple aphids were in fact a different species, the spirea aphid, Aphis spiraecola (Patch). Both species have similar life histories and feeding habits. If you suspect the presence of spirea aphids, contact a specialist familiar with these aphids for help in identifying them. They look much like apple aphids. Winged adult apple aphids have dark-colored veins in their wings; spirea aphids have wings with light-colored to transparent veins.

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Created: June 11, 1999