458 SYNOPTIC COLLECTION. 



sects and the pupa (fig. 3) becomes a winged male (fig. 

 4) ; but if the larva is to be a female, it remains in the 

 pupa-case (fig. 5, female with split pupa skin) and becomes 

 little more than an egg-sac (fig. 6). Its legs and antennae 

 are lost and the wings never develop ; in fact, it has no 

 external features that would place it in the order Lepidop- 

 tera. 1 When egg laying is accomplished, little is left of 

 the body of the parent. The " weather-beaten bags," full 

 of yellow eggs, are tightly fastened to the twigs of trees 

 and in this secure situation usually pass the winter suc- 

 cessfully. 



Other niDths belonging to the generalized Frenatae and 

 affording illustrations of specialization by reduction are 

 the Cossidae or carpenter moths, the larvae of which are 

 borers. Like the young of the Cerambycidae or boring 

 beetles these larvae are more or less grub-like in form, 

 and, although thoracic legs and prop-legs are present, they 

 are reduced in size and are not seen in a dorsal view (PI. 

 1 163, fig. i, young caterpillar of Cossus centerensis Lintner, 

 or the poplar goat moth ; fig. 2, mature caterpillar, three 

 years of age). The larvae excavate burrows in wood by 

 means of their strong black mandibles, and one has been 

 known to bore through a large leaden bullet which was 

 embedded in an oak tree. 2 



At the end of three years a pupa cell or cocoon (fig. 3) 

 is formed which is apparently an enlarged and more care- 

 fully finished burrow. Filling the exit end are coarse 

 and fine wood-scrapings through which the pupa (fig. 4, 

 9 ) passes to the exterior where it becomes the winged 

 insect (fig. 5, 9 , showing ovipositor). 



The reduced condition of the legs is carried still further 

 in the Eucleidae or slug caterpillar moths. In these lar- 

 vae neither legs nor prop-legs can be seen in a side view 

 and the larva appears to be legless. The prop-legs, in 



1 Lintner, ist Ann. Rep. Ins. N Y., 1882, p. 82. 



2 U. S. Dep. Agric., Div. Eat., Bull. 10 (n. s.), 1898, p. 88. 



