io6 



these are moths of several families, whose caterpillars feed on 

 seeds and fruits and are imprisoned when herbarium specimens 

 are made. These are, however, usually unable to complete their 

 transformations and are only exceptionally of use to students of 

 the Lepidoptera. Many snout beetles live in the same manner 

 but most of them must transform from grub to beetle in the 

 earth, hence we can usually learn but little about them from 

 herbarium material. 



Some Cynipid gall-wasps make galls in the substance of seeds 

 (particularly acorns), and several groups of Chalcidoidea 

 (usually parasitic upon other insects) produce galls in seeds or 

 feed directly on the substance of seeds. These Hymenoptera 

 complete their transformations within the pods or seeds, and 

 useful material of them can sometimes be obtained by the exam- 

 ination of herbaria. The snout beetles of the genus Apion in- 

 clude many species living in fruits or seeds. 



The group most frequently found in herbaria are the seed 

 weevils of the family Bruchidae, most often found in the pods 

 or seeds of legumes. These beetles are, like the legumes, most 

 abundant in tropical and subtropical regions, but some species 

 reach northward into Scandinavia, Kamchatka, and Alaska. 



The Bruchidae have worked out interesting methods of en- 

 tering the immature seed as larvae and leaving it as adults after 

 it has ripened. The eggs are usually cemented firmly to the pods 

 about the time they have reached full growth but are still green. 

 The eggshell serves as a point of support for the young larva in 

 eating its way into the pod, bracing itself between the eggshell 

 and pod by means of a transverse pectinate ridge on the first 

 body segment, characteristic of the first larval stage of the 

 Bruchids. 



Once within the seed, the larva eats a surprisingly small por- 

 tion of food for its size. Before pupating, it prepares the way for 

 its own escape as an adult beetle by making a circular window, 

 closed only by the cuticle of the pod or seed. It then compacts 

 the debris resulting from its feeding by a cement, and the whole 

 hardens into a coarsely fibrous silk-like cocoon. After it has 

 transformed and is ready to emerge, the adult extends its head 

 and with its sharp-pointed jaws traces a perfect circle around 

 the membranous window separating it from the outside world. 



