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Nature Notebook – Wooly Alder Aphids

If you walk around wetlands in the fall you may notice a white, cotton candy-like growth on an alder or maple tree. Don’t try to eat it because this is actually a group of insects called wooly alder aphids. They are sap eaters and use their food to create protective waxy, stringy “hairs.”

The 1/8th inch insects, prociphilus tessallatus, also can create a sweet honeydew from their abdomen with the excess food they eat. The honeydew contains water and vital nutrients, which some other insects have realized is a good source of nutrition.

One insect in particular, the ant, has formed a mutualistic symbiotic relationship with these aphids, and has been described as the aphids “ranchers.” The ants will protect a colony of wooly alder aphids from other predatory insects, and in return can use their antennae to tickle the aphids and get sweet honeydew from their abdomens.