Spruce Aphid (Elatobium abietinum) Infestation

Observation: Here are a couple of photos that show the effects of 2 warm winters in a row. I live in Kake, which is in the heart of Southeast Alaska & the Tongass National Forest. We had 2-3 warm winters which encouraged the aphids to multiply. Usually the cold winter temperatures keep them in check. We had a cold winter 2 winters ago and the Spruce trees recovered. In looking at the tree photos, you can see where the needles dropped off and haven’t recovered. You can see at the ends of the branches, healthy needles. Still not sure about this past winter, but so far I haven’t seen any unhealthy needles. Edna Jackson

Alaska Entomological Society Consult: Elizabeth Graham, Entomologist writes, "These Sitka spruce trees are likely suffering from Spruce aphids Elatombium abietinum (Walker). These are sap sucking insects with origins in Europe. With warming climate the aphids are moving further north. Infestations of Spruce aphid is related to climate change because of the importance of temperature to control aphid populations. When winter temperatures drop below 14 degrees Fahrenheit, it kills aphids. After warm winters you see a lot of aphids. They spent first half of the winter under the bark but come out and feed in February and you can start to see the damage in April. Many of the unhealthy spruce trees in Juneau had aphids. When there are a lot of aphids they can really weaken the trees. Stressed trees are unattractive but also become vulnerable to other kinds of tree disease." Source: USDA Forest Service, Forest Health Protection, Juneau, AK. For more information contact the U.S. Forest Service Alaska Region.