New arrivals

This weekend, I went in search of the source of the woolly alder aphids (Paraprociphilus tessellatus) that have been swarming my neighborhood.  When on tree branches, these aphids form white, woolly masses that should be easy to spot.  I don't have their host plants (alders and maples) in my yard, but I thought some of those trees must be nearby.  I checked the alders in a nearby park, but their branches appeared clean.  If it hadn't been windy, I might have gotten a clue about where to look from the density of the aphid cloud.  As it was, I didn't see any aphids flying at all.

Wherever they had come from, the woolly alder aphids were still all over my backyard.  Some were sitting on foliage, presumably sheltering from the wind; quite a few others had been caught in spider webs.  While looking for the woolly aphids, I also discovered several more typical aphids -- ones that might be content with the plant selection in my yard.

A winged aphid on a morning glory leaf.

A winged aphid surrounded by her juvenile offspring on a rose leaf.

For much of the year, aphids reproduce asexually.  Without mating, the females can give birth to many live daughters, which are soon ready to produce their own daughters.  Therefore, a single aphid can quickly generate a large population. 

However, there is little chance that these new aphids will pose a threat to the plants in my backyard.  Starting tomorrow night, we are expected to have a series of hard freezes.  Even if the aphids survive the frost, there won't be much more damage that can be done to the plants this fall.