Apple Grain Aphid

The apple grain aphid (aka apple-grass aphid) is the most conspicuous aphid in apple orchards in the early season. It appears at the green tip stage before eggs of other aphids have hatched. Though it can be alarming to see buds completely covered with the dark green aphids, they do little damage to apples.

Apple grain aphid (AGA) rarely causes damage to apple. But since it is generally the first to appear on apple buds in the spring and is often abundant, it often arouses the concern of the grower.The primary hosts, on which eggs are placed for the winter, are apple, hawthorn, pear, quince and plum. During the spring and summer, this aphid moves to various grass species. The overwintering eggs are a shiny black, indistinguishable from the other aphids overwintering on apple. Newly hatched nymphs are a dark green color. There is a slightly lighter green area running down the back .

The antennae, legs and cornicles are very dark. The antennae are short, reaching about to the end of the thorax. Those of young rosy apple aphid stem mothers reach to about half the length of the abdomen. The cornicles of AGA nymphs are short, barely swollen discs. The young nymphs are generally hard to distinguish without magnification, unfortunate given the great disparity of damage potential between the species. The mature stem mother is 8/100 inch (2-2.15 mm) long. The mature aphids have a darker green stripe along the middle of the back.

Life cycle:The egg is small, oval and shiny. Though dark green, it cannot easily be distinguished from other aphid species’ eggs. Eggs are laid on small branches, fruit spurs and terminals.The newly hatched nymph is dark green at first but turns lighter green. It has short cornicles or protuberances at the end of its abdomen.The older nymph and adult is light green with a darker green stripe down the middle of the back and crossbars of the same color.The apple grain aphid overwinters on apple trees as an egg near buds or on terminals, fruit spurs or larger branches. During the pruning season, eggs are often found by the hundreds. Eggs begin to hatch in spring when apple buds show the first green tissue. Nymphs feed on opening leaves, usually on spurs rather than watersprouts or terminals. Newly hatched aphids can be killed by unusually cold spring temperatures.

The nymphs mature into wingless females that produce young without fertilization. One female can produce 100 offspring. Most second generation apple grain aphids have wings and migrate to summer hosts such as grain crops and grasses. The second generation aphids without wings produce a third generation. Those adults all have wings and begin to migrate from the apple trees about petal fall. By the end of May, what appeared to be a serious aphid problem will have vanished. The aphids produce several more generations on the summer hosts. Winged females return to apple trees in the fall. Males migrate back to the orchard in late fall and mate with the females, which lay overwintering eggs on apple twigs.

Damage:all apple varieties are attacked by rosy apple aphid, ‘Cortland’, ‘Ida Red’, and ‘Golden Delicious’ are particularly susceptible. Feeding on the leaves of fruit clusters often results in stunting and malformation of the fruit. For this reason, rosy apple aphids are the most serious aphids attacking apples. Honeydew produced by the aphids promotes the growth of sooty mold as well. This becomes more noticeable as the fruit develops. Problems usually begin to appear after petal fall and by mid summer the aphids move to alternate hosts.

The aphid overwinters on apple trees as eggs laid on twigs, bud axils, or in bark crevices. The black eggs are 1/2 mm long and football shaped.Shortly after silver tip the eggs hatch. The nymphs’ color changes from dark green to purple as they grow. The overwintering eggs give rise to only female aphids which give birth to live young. The aphids continue to reproduce on apple until summer, then winged forms are produced which migrate to other hosts such as dock and narrow-leaved plantain to spend the summer. In the late fall, winged forms migrate back to apples and lay eggs in bark crevices and on twigs.

Control:The most commonly observed predator of green apple aphid is an orange maggot of the gall midge species Aphidoletes aphidimyza. The mosquito-like adult midge seeks aphid colonies as sites for laying eggs that hatch into predatory maggots. Maggots are 0.3 mm long when first hatched and 2.5 mm when fully grown. They inject a poison into the aphid prey, then suck out the aphid’s body fluids. Once fully grown, maggots drop to the ground and pupate in a cocoon in the top layer of soil.

Practices that minimize the growth of succulent leaves will aid in suppressing this pest. Fewer green apple aphids are found in trees that are summer pruned to remove water sprouts and that had minimal fertilizer treatment.In commercial orchards, endosulfan (Thiodan), dimethoate (Cygon), chlorpyrifos (Lorsban), or methomyl (Lannate) can be used to control green apple aphid. In home plantings, diazinon or insecticidal soap can be used for aphid control. Thorough coverage of leaves is needed for soap or diazinon to be effective.

If you have any questions about how to get rid of ants check out the rest of our website or go to our blog at http://nypestpro.blogspot.com.

Beyond Pest Control.

Our pest control specialists service all NYC boroughs, including Queens, Brooklyn, Bronx, Manhattan, Long Island (both Nassau & Suffolk counties), Staten Island and even both Westchester & Rockland counties.