268 LARCH CHEATER ITS GENERIC PLACE. PARASITES. 



crest upon the hind part of its thorax. In both these species 

 the hind margin of the wings is entire and not scalloped as they 

 are in the genus Gastropacha, and their wings are more thin, 

 delicate and semi-transparent. In G. Americana the second vein 

 which is given oft* from the outer side of the outer principal 

 vein of the fore Avings forks forward of its middle and both its 

 branches terminate in the outer edge of the wing forward of its 

 apex. In these two species the same vein forks much beyond 

 its middle, the two branches diverge much more strongly, and 

 both end in the hind margin of the wing, rather inside of the 

 apex, the tip of the wing here being rounded and not forming 

 an angle as it does in the former species. Such differences for- 

 bid our associating these insects together in the same genus. 

 And as their deceptive appearance is one of their most promi- 

 nent characteristics in each stage of their lives, the generic name 

 Plancsa (Greek «rXavos ? a deceiver,) or in English, the cheaters, 

 may appropriately be given to the Velleda and the species which 

 we have here described. The best distinctive name for the lat- 

 ter will be that of the tree which it infests. We therefore pro- 

 pose calling it Planosa Laricisj or the Larch cheater. 



From one of the four cocoons mentioned above, came five 

 parasitic insects, which had destroyed the pupa. These gnawed 

 their way out of the cocoon at short distances from each other, 

 each making a round hole, the edges of which were rough and 

 jagged. They were all females of a pretty species of Ichneu- 

 mon fly (Family Ichneumoniok Order Hymenoptera) 0.30 long, 

 of a black color with the abdomen and legs tawny red and the 

 hind feet, scutel and a band on the middle of the antennas 

 white. They pertain to the genus Phygadeuon of Gravenhorst, 

 which genus is distinguished by having a depressed abdomen nar- 

 rowed at its base into a slender stalk or petiole, a protruded ovi- 

 positor, the joints towards the base of the antennae somewhat 

 long and the small cell in the middle of the fore wings with five 

 sides. This genus embraces a number of described species, most 

 of which have the abdomen red or red and black, with Che scu- 

 tel also black and not pale as we find it in the present instance. 

 This insect may be named 





