Giant Willow Aphid

Pterochlorus viminalis

Jeff Schalau

The Giant Willow Aphid is one of many species of aphids. The common names of most aphids have the name of a host plant in it. This is because most species of aphids eat a particular plant or group of plants. Giant Willow Aphids eat willows.

Because there are so many species of aphids, it would be impossible to do species pages for all of them; however, most are similar in many ways to Giant Willow Aphids, besides being smaller.

Giant Willow Aphids are large aphids, growing up to 1/4 inch long. Since these are "big" ones, you can tell that aphids are tiny insects.

Giant Willow Aphids are usually found on willow trees.

Catherine Matilida Collins


Giant Willow Aphids have a pear-shaped body with a small head and long antennae. They are brown with black spots. Sometimes these aphids appear gray, because of a waxy white dust that gets on them. The wax is made from two short black tubes that stick out from their abdomen.

Giant Willow Aphid nymphs are young aphids that are not fully grown yet. Nymphs are an amber color and they are transluscent (light can pass through them). Nymphs eat and grow quickly, shedding their skin several times before they become adults.

The life cycle of aphids gets confusing. We'll start with the eggs.

Giant Willow Aphid eggs hatch in the Spring. The only aphids born are wingless females. When the wingless females are fully grown they lay more eggs. You might ask, how can they lay eggs without mating? They can't mate without males, and so far all we have are wingless females? The answer is this: some females of certain animals can give birth by themselves. This is called parthenogenesis (pronounce: par-thee-no-jen-e-sis). Through parthenogenesis, our wingless females did not need male aphids and they laid more eggs. What hatches out of these eggs? More wingless females.

This will continue for several generations. The second batch of wingless females will grow quickly and, through parthenogenesis, lay more eggs. There will be several batches of wingless females. This happens very fast, because aphids grow quickly.

Finally, one of the batches of eggs will hatch as winged females (still no males!). These females will use their wings to fly to some other species of plant. So far, all the aphids born had been living on and munching a willow tree.

These winged females will lay eggs on the new plant. These eggs will hatch as wingless females (again!). Several more generations will continue to be born, all as wingless females. Then, finally, another batch of winged females will be born. These females will fly back to the willow tree where they started. There, they will lay eggs which are, again, wingless females.

Several generations of wingless females will be born on the willow tree, until finally Fall arrives. Once it is Fall, one of the egg batches will not be born just as wingless females. Instead, wingless females and males will be born. The aphids will mate, and the females will lay eggs.

The new batch of eggs will stay on the willow tree until Spring, when wingless females hatch and the cycle starts over.

Curtis Swift

As the Giant Willow Aphid life cylce continues, huge aphid colonies are built. These colonies attract predators, including: mantids, ladybug beetles, parasitic wasps, lacewings, and others. Giant Willow Aphid colonies are usually seen close to the ground.

Aphid colonies also attract ants. Aphids release a liquid called honeydew. Ants, and some other insects, love to eat honeydew. Some species of ants even "farm" aphids. They guard and protect the aphids so that they'll have plenty of honeydew to eat.

Giant Willow Aphids drink the juice of willows. They get this from leaves, stems, and flowers. Aphids can do great damage to their host plants when colonies are large.

When females lay eggs for the Winter, they hide them in cracks between the tree bark.

When aphids are disturbed, they kick all six of their legs with a lot of energy.

Relationships in Nature:


Black Willow

Convergent Ladybug Beetle

Black Willow

Black Carpenter Ant Mu

Chinese Mantid

Black Willow H

Green Lacewing

Garden Centipede

Red-backed Salamander

Spotted Salamander

Spring Peeper

Common Black Ground Beetle

Eastern Newt

Green Darner


Pennsylvania Firefly

Rabid Wolf Spider

Daring Jumping Spider

Ebony Jewelwing

Ring-legged Earwig

Downy Woodpecker

CommonWater Strider

Common Whitetail

Spined Micrathena

Relationship to Humans:

Giant Willow Aphids, along with other aphids, can be great pests. Huge colonies can damage trees and plants that aphids feed on. Fortunately, aphids have a lot of predators who help control them.


Pterochlorus viminalis


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