628 



AN INTRODUCTION TO ENTOMOLOGY 



with a plug of silk, which is so formed that it can be 

 pushed out by the adult moth when it is ready to emerge. 



Some members of the family are leaf-rollers. 

 Figure 770 represents a l^af rolled by a gelechiid larva, 

 probably Anacdmpsis innocuella. This species infests 

 poplar. 



The pink bollworm, Pectinophora gossypiella. — This 

 species is regarded as one of the most destructive cotton 

 insects known and ranks among the half-dozen most 

 important insect pests of the world. It often reduces 

 the yield of lint fifty per cent, or more and materially 

 lessens the amount of oil obtained from the seeds. 



The adult is a small dark-brown moth, with a wing- 

 expanse of from 15 to 20 mm. Figure 767 represents 

 the shape and the venation of the wings. The larva 

 eats the seeds and tunnels and soils the lint, causing 

 the arrest of growth and the rotting or premature and 

 imperfect opening of the boll (Busck). 



A detailed account of this pest, illustrated by many 

 figures was published by Busck ('17). 



Family BLASTOBASID^ 



The scape of the antennae is armed with a fringe of 

 strong bristles, or pecten. The labial palpi are slender 

 and upturned or vestigial. 



The discal cell of the fore wings(Fig. 771) is long 



Fie 770— compared with the lengths of the apical veins (R2 to 



Leaf rolled CU2) ; and these veins arise from the extreme end of 



by a gele- the cell. As vein Ri arises near the base of the wing it 



chiid larva, jg unusually distant from vein R2; to make up for the 



resulting weakening of the wing, the membrane is more 



or less thickened along the costa; this thickening is the so-called 



stigma. The hind wings are lanceolate, and rather narrower than the 



fore wings. Veins Rg and Mi are well separated at the end of the 



discal cell. Veins M2, M3 and Cui are close together or coincident. 



About one hundred species have been described from our fauna; 

 among them are the following. 



The acorn-moth, Valentmia glandulella. — The larva of this species 

 lives as a scavenger in acorns that have been destroyed by a,com- 

 weevils. Balaninus. The moth lays an egg in the destroyed acorn 

 after the beetle has left it, and the larva hatching from this egg 

 feeds upon the crumbs left by the former occupant. The larva passes 

 the winter within the acorn. The moths emerge at various times 

 throughout the summer. 



