. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. DESCRIPTION OF SUMMER FOEMS. 59. Fig. 12.—The spring grain-aphis: Young, first instar. Enlarged; actual size, mm. (Original.) Measurements of antennal joints (average from 16 specimens): I, mm.; II, mm.; Ill, mm.; IV, mm.; V, mm.; VI, base, mm.; VI, filament, mm.; total length, mm. They are slightly pruinose in each stage. The material from which these data were taken is mounted on slides and is in the collections of the Bureau of Entomology, bearing Webster nu
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. DESCRIPTION OF SUMMER FOEMS. 59. Fig. 12.—The spring grain-aphis: Young, first instar. Enlarged; actual size, mm. (Original.) Measurements of antennal joints (average from 16 specimens): I, mm.; II, mm.; Ill, mm.; IV, mm.; V, mm.; VI, base, mm.; VI, filament, mm.; total length, mm. They are slightly pruinose in each stage. The material from which these data were taken is mounted on slides and is in the collections of the Bureau of Entomology, bearing Webster number 5151. The first generation, or stem mothers, is always wingless. All of the following gener- ations differ in color, more especially in the first and second instars. The adult stem mothers, so far as we have been able to learn, never have the darker green dorsal stripe. The antennae are shorter throughout the different instars, and in the adult also, than in the summer forms. DESCRIPTION OF THE SUMMER FORMS. First instar (fig. 12).—Before first molt: General color very pale green, the thorax probably the palest; head pale green with a dusky tinge; eyes brownish black; tip of cornicles black, bases dusky; articula- tion of femora and tibiae and distal portion of tibiae dusky; tarsi black; two apical segments of antennae black, remaining segments concolorous with head. Antennae 4-segmented. Measurements of antennal joints (average from 3 specimens): I, mm.; II, mm.; Ill, mm.; IV, base, mm.; IV, filament, mm.; total length, mm. Second instar (fig. 13).—Before second molt: General color slightly paler now; head not dusky; eyes same as in preceding stage; legs with a more greenish tinge now, other- wise same as in previous stage; the two basal joints and the proximal portion of the third joint of antennae concolorous with head, other portion black. Antennae 5-jointed. Measurements of antennal joints (average from 2 specimens): I,
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