Aphids: 'They're baaaaack'

The smokey-winged ash aphids are back by the thousands and they are driving us to distraction. A friend of mine asked me to report on the bothersome aphids that had shown up in clouds recently and were becoming more than a nuisance. I became more curious about these tiny bugs when I was out at the grill cooking dinner.

As I continued to be tormented by the aphids at the barbecue grill, I realized my moving and trying to swat them with my hand and even the spatula was to little avail and provided only temporary relief.

Finally, I discerned that the only thing that seemed to provide relief from the aphids was the wind or at least a small breeze to blow away the bothersome tiny bugs.

Every fall we and other people in north Idaho briefly have to deal with a cloud of fluttery little blue insects. Flying in mass for a week or two, they’re an incredible nuisance for walkers, joggers, rollerbladers, bikers, or anyone else who likes to be out of doors. The smoky-winged, ash aphids are a nuisance, but harmless to humans except for the sneezes that they cause and if we would happen to breathe them in.

The smokey-winged ash aphids have a life history that alternated between two different host plants. For most of the summer, these aphids have been living underground, sucking the juice from fir tree roots.

During the time they are underground they multiply asexually. The aphids gather in wax-covered colonies that are often tended by ants collecting honeydew. In the fall, male and female winged forms emerge from the ground and seek out ash trees where they mate and lay eggs in the crevasses of the ash tree bark. During the following spring, the eggs will hatch and the baby aphids or nymphs will crawl to the ash leaves and feed on sap until early summer when it’s time to move back to fir roots.

Aphids have sucking, not chewing, mouthparts and suck the juices out of leaves and young soft shoots of plants. Aphids are a favorite food of ladybugs. Aphids are often kept as ‘pets’ by ants. The ants protect the aphids from other predators and in return the aphids give the ants a sweet nectar that they produce as a by-product of metabolism.

Homeowners who see high infestations on their ash trees in the fall may want to drench the trunks and branches with insecticidal soap or dormant oil before bud break (initiation of a growth from a bud) next spring to kill overwintering eggs.

The hordes of the small blue bugs will be around for a few more days or weeks. The number and duration of these swarms is dependent on the weather and some years they are more prevalent, but a freezing night will spell a quick end to the “blue bugs of autumn.” For more information, contact WSU/Pend Oreille and Boundary County Extension and www.mtagalert.org. Enjoy the beginning of fall! Information: visit www.naturallynorthidaho.com