THEIR RELATION TO PLANTS 69 



we left our specimens undisturbed we would probably 

 get thirty more the next year thereafter and the re- 

 mainder the third year following. This seems to be 

 rather a wide-spread provision for tiding insects over 

 a bad season and, not only in the snout beetles but in 

 many other groups, single-brooded species that pass 

 the winter in the pupal stage, may lie over for one 

 or even two vears after the bulk of the brood has 

 become adult. 



By virtue of this provision for placing eggs, many 

 of the snout-beetle larvae are feeders in blossoms, fruits 

 and seeds, and enormous damage is caused to trees 

 and plants by limiting their seed bearing powers. When 

 these fruits are of commercial importance like the plum, 

 the horticulturist classes the "plum curculio" as a 

 first class pest and a subject for investigation by the 

 economic entomologist. If I mention once again the 

 cotton-boll weevil, and cite as a further example of seed 

 destruction the strawberry weevil, the danger of this 

 sort of insect to plant life may be appreciated. It is 

 of course the larva that does the injury, and curculio 

 larvae are all more or less grub-like in character; mostly 

 white like the generality of internal feeders, and usually 

 with a brown chitinous head furnished with well-de- 

 veloped jaws or manidbles. 



Blossoms, fruits and seeds furnish only one article 

 of diet for weevils and their larvae: many bore into 

 the stems of herbaceous plants, as the rhubarb weevil; 

 others bore into wood tissue like the w^hite pine weevil, 

 and the latter, by killing off the leading shoots, fre- 

 quently distorts a tree to such an extent as to make 

 it commercially useless. A comparatively small number 

 are external feeders on plant tissue like the clover- 

 leaf beetle; a few make tubes or other cases out of the 

 leaves on which they feed, and some cause galls or 



