LEPIDOPTERA 



235 



or frequently pectinate in the males. Two ocelli are almost always pres- 

 ent. The labial palpi are well developed, and in some species quite prom- 

 inent. The maxillas are quite long and stout in most species. The thorax 

 is heavy and stout. In the majority of the species the scales on the dorsal 

 surface of the thorax are turned 

 up more or less, forming tufts. 

 The abdomen is conical and ex- 

 tends beyond the anal angle of 

 the hind wings when these are 

 spread. Figure 410 shows the 

 type of venation. 



The majority of the larvae 

 are naked, of dull colors, and 

 provided with five pairs of 

 prolegs. As a rule they feed 

 on the leaves of plants, but 

 some are borers and some gnaw 

 into fruits. Among them are 

 some of the more important in- 

 sects injurious to agriculture. 



The family Noctuidas has 

 been divided into many sub- 

 families. In the following 

 pages the more important 



r ,1 1 • Fig. 410. — Wings of a noctuid, Agrolis ypstlon. 



of those represented m our 



fauna are briefly discussed, in order to show, as well as possible in a 

 limited space, the variations in form included in this family, and to indi- 

 cate the position of our more important species. 



The Deltoids 



There is a group of moths, the deltoids, which are placed at the foot 

 of this family on account of their apparent relationship to the geometrids 

 and to the pyralids. These. moths are usually of dull colors and of medium 

 size. The name deltoids was suggested by the triangular outline of the 

 wings when at rest, which is well represented by the Greek letter delta. 

 When in this position the wings slope much less than with other noctuids, 

 the attitude being more like that assumed by the geometrids. Two 

 species of this group will serve as examples. 



The green clover-worm, Plathypena scabra. — This is a common del- 

 toid. The usual food-plant of the larva is clover, but it occasionally 

 defoliates peas, beans and lima beans. It is a slender green worm meas- 

 uring when full-grown f of an inch in length and only about -^ of an inch 

 in width in its widest part; it has a narrow subdorsal whitish line and a 

 lateral one of the same color. When ready to 

 transform it webs together several leaves and passes 

 the pupa state in the nest thus made. The 

 adult (Fig. 411) is a blackish -brown moth, with 

 an irregular grayish shade on the outer half of the 

 fore wings, and with very broad hind wings. The 

 palpi, which are not well shown in the figure, are 

 long, wide, and flattened; they project horizontally like a snout. 



bra. 



Fig. 411. — Plathypena sea- 



