By Donald Lewis
Extension Entomologist
Iowa State University

As we glide through late summer and into fall on our way to winter, several different species of aphids are making their presence known. None are incredibly important, but they are noticeable.

One of the noticeable aphids filling the air right now is the soybean aphid, so now everyone has a chance to get up close and personal with this aphid, not just farmers. The soybean aphid has an interesting life cycle that forces it to move from one part of the landscape to another two times each year. Soybean aphids that started the summer on buckthorn trees and shrubs flew to the soybean fields in early June. Now that the beans are ripening, winged aphids produced in the fields are migrating back to the trees. It is the return movement of billions (could it be trillions?) of aphids that people have noticed, as clouds or swarms of aphids pass above lawns, sidewalks trails, bike paths and the landscape in general. The annoyance caused by swarms of aphids is widespread but spotty, with calls from around Iowa and neighboring states.

The bad news is that the aphids are a nuisance and get into the mouths, noses and eyes of joggers and bike riders. The good news is they are not dangerous to you, your pets or other animals or your landscape.They can't bite, they don't carry diseases to people and they can't sting. They do not attack garden vegetables, fruits or landscape plants. 

These swarms of aphids are a temporary problem and as the weather changes and as the aphids either die or reach their destinations and start mating and laying eggs, the problem will subside. Though we may see winged aphids flying around until the end of October, the worst is probably already over.

Flying Fuzz Balls

Woolly aphids live on several different trees and shrubs. The name describes what is peculiar about this group: The body of the aphid is covered with a white fluffy wax that resembles wool.  In late summer you may notice colonies of woolly aphids clustered on the twigs and shoots of hawthorn and crabapple trees. Infestations are sporadic and vary from trees to tree, variety to variety and place to place.

Woolly aphids on hawthorn and crabapples feed on sap from the plant but are more alarming than damaging, especially late in the season. Parasites, predators and even heavy rainfall will help reduce the populations. If you believe the natural population controls need your help, you can use a forceful stream of water from the garden hose to dislodge the aphids or prune and remove selected, heavily infested stems and water sprouts.  Spraying with insecticide is rarely justified.

Earlier in the season there were woolly aphids of another species on the leaves and shoots of maple trees. In most cases the sap loss from aphid feeding is not significant to the plant and control is not practical. In some cases infested leaves may droop or shrivel and drop prematurely.This does not reduce the vigor of healthy trees.

When the woolly aphids disperse from one host to another, as described above for soybean aphid, the winged forms are still capable of producing the white, waxy strands on their body.  This produces the hallucinogen-like, unmistakable sight of small cottony white fuzz-balls flying through the air under their own power. If you are deft enough to gently catch one of the apparitions you see a plump bluish-black body and transparent wings pulling the cottony tuft through the air. These flying fuzz balls, like the aphids on the twigs, may cause alarm, but there is no permanent damage. The flying woolly aphids are a wonderment. They are intriguing, not harmful. Relax and enjoy the fascination of Nature.

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