PHYTOPHAGA BRUCHIDAE 



277 



thickened. This comparatively small family includes about 

 700 species of small, unattractive beetles. The larvae live in 

 seeds ; hence some of the species are liable to be transported by 

 means of commerce ; some of them do considerable injury ; peas 

 and beans being specially subject to their attacks. They are 

 able to complete their gro^¥th with a very small amount of 

 nutriment, some of them consuming only a portion a little larger 

 than themselves of a bean or pea. The larvae are fat maggots 

 without legs, but Eiley has discovered that the young larvae of 

 Bruchus pisi and J5. fabae have, when first hatched, three pairs 

 of legs which are subsequently lost. They also have peculiar 



Fig. 141. — Bruchus 

 pisi or pea-weevil. 

 A, Young larva ; 

 B.prothoracic spin- 

 ous process ; G, 

 post-embryonic 

 leg, greatly magni- 

 fied ; D, pea-pod, 

 with tracks of 

 entry ; E, portion 

 of pod, witli egg, 

 and .the subse- 

 quently formed 

 track, magnified ; 

 F, imago. (After 

 Biley.) 



spinous processes on the pronotum. Both of these characteristics 

 may be correlative with the transient differences in the activities 

 of the larva, for the little creature is not at first located in the 

 pea, but mines a gallery in the pod, in which it moves about, 

 subsequently entering the pea and losing its legs. There is a 

 good deal of difference in these respects between the two species 

 — B. pisi and B. fabae — examined by Eiley, and as but little is 

 known of the life-histories of other Bruchidae it is probable that 

 still greater variety prevails. Heeger has found that Bruchus 

 lentis sometimes requires two seeds to enable it to complete its 

 growth ; .it is, notwithstanding its legless state when half-grown, 

 able to migrate by dropping to the earth, and dragging itself 

 along by its mandibles till it comes to another pod into whicli it 

 bites its way. 



The family has, until recently, been placed in the Ehyncho- 



