Post-Script on Insect and Disease Conditions Report on October 3, 2023

Post-Script on Insect and Disease Conditions Report on October 3, 2023

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Maine Forest Service

Post-Script on Insect and Disease Conditions Report on October 3, 2023

It was brought to our attention that one of the articles in the October 3 version of the Insect & Disease Conditions Report for Maine, which you received earlier this week, was incomplete. The last paragraph was missing from the section on Woolly Alder Aphids.

Here is the article in its entirety:

Woolly Alder Aphid (Prociphilus tessellatus) –

If you have taken a look at the alder in your yard recently you may have noticed white cotton like flocculence produced by woolly alder aphids. These aphids have a somewhat complex lifecycle that involves multiple hosts. The lifecycle begins with the eggs that are laid on silver maple (Acer saccharinum) and occasionally red maple (Acer rubrum). These eggs hatch in the spring and begin feeding on the new tender leaves. At this stage the aphids are all female and reproduce parthenogenetically which allows populations to grow fast as they are able to clone themselves without mating. As summer gets underway a winged generation of both males and females is produced which fly to alder, in Maine this is typically speckled alder (Alnus incana). As fall approaches and the length of daylight becomes shorter another winged generation of winged males and females is produced. Occasionally males and females are produced when they first arrive on the alder, however they do not become reproductively mature until they receive the shortened daylight cues. These end of season reproductive individuals return to their silver maple hosts, mate and lay eggs in sheltered places on the bark.

These aphids are very important to their native ecosystems since they provide food for lacewings, parasitic wasps, as well as the adults and larvae of lady beetles, hover flies and the harvester butterfly (Feniseca tarquinius), the only obligate carnivorous butterfly larva in the continental U.S. (the adult harvesters and hover flies feed on honeydew exuded by the aphids). If you see these aphids in your yard, consider leaving them, as they typically do not cause lasting damage to their host plants.

An alder trunk with much white fluff on its side.

Image: Woolly alder aphid colony on speckled alder, Blue Hill ME

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