Gall adelgid
| Cooley Spruce Adelgid | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Superfamily: | Phylloxeroidea |
| Family: | Adelgidae |
| Genus: | Adelges |
| Species: | A. cooleyi |
| Binomial name | |
|
Adelges cooleyi (Gillette, 1907) |
|
The gall adelgid (Adelges cooleyi) is an adelgid species that produces galls in spruce trees. They infect the new buds of native spruce trees in the[foothills of the Rocky Mountains in the spring. They also attack blue spruce to a lesser degree. The insects complete two generations within the year. They require two different trees for its life cycle, the second being the Rocky Mountain Douglas-fir. They may also attack Sitka, Engelmann, or white spruce. The many different species of adelgids produce different galls on different spruce species.
The Cooley spruce gall adelgid (Adelges cooleyi Gillette) is mainly a western species that usually alternates between white spruce and Douglas fir. It is rare in eastern Canada. In Ontario, the galls are found mostly on Colorado spruce.
The infection is most noticeable on Cooley spruce in the spring, May to June, when the galls appear. This infection may be mistakenly diagnosed to as caused by worms, grubs, or even as a sex organ of the spruce. Spruce pollen, however, is released from a smaller structure that lacks needles. The galls are characterized by this pineapple-like form, with a length of 0.5 cm to 8 cm depending on the growth capacity of the tree. Most galls take on a pink, red, or even deep purple colour while the needles usually remain green. The segments of the new bud that have this gall form will die after the aphids leave in the summer. Once on Douglas fir, the adelgids consume the needles, but do not form galls.
In the fall, the immature female adelgid, small, globular, and wingless (1.2-1.7 mm), finds a spruce on which to overwinter. In the spring when the winter thaw occurs, the female matures and lays some eggs in what resembles sacks (totalling several hundred eggs) on the branches near the developing buds. These, in fact, are not sacks, but individual tufts of white waxy threads that protect the eggs. The females prefer areas on the spruce where they have greater protection from the elements, especially wind. These female individuals have an obvious patch of white wax wool as a covering. Their mouthparts consist of thread-like stylets which are used to penetrate into vascular bundles for feeding.
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Wikipedia