THE HyMENOPTERA OF MINNESOTA 159 
stripe along the middle of the back. Eggs are laid in June and the 
winter is spent below the surface of the ground, in the larval stage, 
not changing to pupa until spring. This species, normally destruc- 
tive, has been observed to prey upon Gypsy Moth caterpillars (The 
Gypsy Moth, Report of Forbush and Fernald, Mass. State Bd. Ag. 
1896, p. 379). For an illustration of the larva of this form see Fig. 32. 
The adult is shown on colored plate 1. 
ARGIDAE 
Agrees with the preceding description of Cimbicidae except as follows: Abdomen 
not sharply angled laterally; antennae not clavate; sternauli or a suture separating 
the mesosternum from the mesoepisternum, present; hind coxae adjoining or nearly 
so; antennae three jointed. 
The Purslane Sawfly, Aprosthema sabriskei Webster, occurring 
commonly in Minnesota, is an interesting form in that it is sometimes 
quite effective in checking the purslane. The eggs are deposited by 
the female in the edges of the leaves. The larvae work within the 
leaf between the two surfaces. The pupal stage occurs in the ground 
and lasts about seven days. 
Other Minnesota 
species are Arge cae- 
rulea Nort., the larva 
feeding on white 
birch; A. clavicornis 
F;, A. humeralis 
Beauv., A. scapularis 
Klug, A. mcLeayi 
Leach, A. pectoralis 
Leach, A. dulciana 
Say, and Stericto- 
phora johnsoni MacG. 
DIPRIONIDAE 
Agrees with the preceding description of Argidae except as follows: sternauli 
wanting; antennae more than six-jointed, furthermore, the first discoidal cell is not 
petiolate, the mesoepimeron is divided into two plates with the sculpture of the dor- 
sal one similar to that of the mesoepisternum, proepisternum not divided into two 
plates; antennae many jointed, serrate in the female, pectinate in the male. 
The larva feed on various pines and on fir. Diprion abboti some- 
times defoliates branches of pine. The species has the habit of throw- 
ing back head and tail when disturbed. D. abietes feeds, in companies, 
on fir leaves until full grown. The whitish, tough cocoons often ad- 
here to the leaves until the following season. Both of these species 
may be quite destructive. D. pinetum, occurs in Minnesota, the larva 
feeding on pine. 
