Green spruce aphid; spruce aphid
Quebec, British Columbia
The spruce aphid, Elatobium abietinum (Walker) (Homoptera: Aphididae), is a pest of spruce in coastal British Columbia. Apparently native to B.C., it was first reported here in 1916, but it was known in Europe as early as 1846.
Damage, symptoms and biology
The spruce aphid prefers old needles and does not usually attack current growth. Most aphids are found on the lower side of needles and are usually concentrated on the lower (shaded) crown, but they often affect the leaders and upper crown. The first signs of feeding in winter or spring are yellow patches on the needles; by late spring the needles turn yellow or brown and then drop with summer's heat. Severe attacks may completely defoliate ornamentals or natural stands and may result in tree mortality; partial defoliation may result in increment loss and dieback of branches. Needle discoloration and needle drop varies according to attack density and weather conditions.
The spruce aphid in British Columbia apparently has only two stages: nymph and adult. As with most aphids, outbreaks of the spruce aphid occur from time to time and the outbreaks are difficult to predict; however, outbreaks often follow mild winters. There is a sharp decline in the aphid population on Sitka spruce between late spring and November. Large colonies develop during the winter and feed during mild periods. Low temperatures, overcrowding, and resultant starvation will reduce their numbers.
In Europe, winged and wingless females produce nymphs all year, even during mild periods in winter. In coastal B.C., only wingless females have been observed reproducing, and these only in late winter and spring. The greatest population increase occurs from late winter to early spring when nymphs develop into wingless females. Winged females appear as temperatures rise in late spring.
Canadian Forest Service Publications
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Piercing-sucking: Has specialized mouthparts for sucking the fluids from plants, thereby causing deformities or killing the affected plant sections.
Information on host(s)
Both native and introduced spruces are the preferred hosts for this insect pest. Sitka spruce (Picea sitchensis (Bong.) Carr.), Norway spruce (Picea abies (L.) Karst.), blue spruce (Picea pungens Engelm.) and other spruces are attacked by this pest on North America's Pacific coast from Alaska to California throughout the range of Sitka spruce. It may occur rarely on some other conifers such as pines (Pinus spp.) and Douglas-fir (Pseudotsuga menziesi(Mirb.) Franco). Infestations in Sitka spruce stands appear to be restricted to the coast; none has been recorded inland.