. An annotated list of the important North American forest insects. Forest insects. The Spruce Gall-Aphid . 9 groups tends to have numerous pores. This form (figure 2), which passes the winter on the hranches of the spruce at the bases of buds, secretes more or less wax in the form of white threads that usually cover the body. LIFE HISTORY The spruce gall-aphids pass the winter as first-stage female nymphs clus- tered in crevices of the stem about the bases of the buds. On severely in- fested spruces the overwintering forms are abundant, there being as many as twenty to thirty about one bud. W
. An annotated list of the important North American forest insects. Forest insects. The Spruce Gall-Aphid . 9 groups tends to have numerous pores. This form (figure 2), which passes the winter on the hranches of the spruce at the bases of buds, secretes more or less wax in the form of white threads that usually cover the body. LIFE HISTORY The spruce gall-aphids pass the winter as first-stage female nymphs clus- tered in crevices of the stem about the bases of the buds. On severely in- fested spruces the overwintering forms are abundant, there being as many as twenty to thirty about one bud. When examined with a lens they are seen to be purplish gray, but to the unaided eye they resemble small grains of gunpowder. By May 5, in 1923, the spruce buds had begun to grow and many of the nymphs had molted. So far as the writers' observation^ have gone, but one molt has been found in this generation, but some molts mav have been missed. The females increase in size, and begin to secrete long, crinkly, curly, white, waxy hairs, and become bluish green in color. They all settle now at the bases of the developing branch buds. The weather continued cold after the above-named date, and the females remained rather stationary in development for a week. By May 16, how- ever, females were found which had just begun to lay eggs. The individuals develop fairly in unison, although there are belated ones here and there that are sometimes a week behind the earlier ones in depositing eggsT By the end of May, in 1923, nearly if not quite all were depositing eggs. There is some evidence to indicate that egg laying is influenced by the develop- ment and activity of the tree. The buds on some trees start much earlier than do those on others, and on ^ those trees which start early the aphids are found to be depositing [ eggs, while on the spruces, which are then still dormant, the aphids are inactive. At least this proved to be the case in some instances which the writers were fortunate enoug
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Keywords: ., bookauthorhopkinsadandrewdelmar, bookcentury1900, bookdecade1900
