|Adelges tsugae close up|
Adelges is a genus of insects which feed on conifers. Excepting galls formed by the spruce gall midge, galls are caused by aphid-like insects of the superfamily Phylloxeroidea (family Adelgidae) commonly known as the spruce gall adelgids. They have complex life cycles, some species feeding exclusively on spruce, others feeding on spruce and an alternate conifer. However, galls characteristic of each species are formed only on spruce. Six generations are usually needed to complete the 2-year cycle, and in the case of species having an alternate host, winged adults about 2 mm long are formed only in the generations that move from one host to the other.
The spruce gall adelgid (Adelges lariciatus Patch) occurs in alternate years on spruce and larch from Alberta to the Maritimes and in adjacent parts of the United States. The pale spruce gall adelgid (Adelges strobilobius Kaltenbach) has a similar range but prefers black spruce or red spruce to white spruce.
- Adelges abietis (Pineapple gall adelgid)
- Adelges cooleyi (Gall adelgid)
- Adelges piceae (Balsam woolly adelgid)
- Adelges tsugae (Hemlock woolly adelgid)