194 



INSECTS INJURIOUS TO VEGETABLES 



The Western Corn Root-worm (Diabrotica longicuniis Say.). 

 — Notwithstanding the general employment of crop rotation 

 as a means of preventing losses by this species, inflicted in- 

 juries are reckoned by millions of dollars annually. Thus in 

 1885 the damage to corn in 24 counties of Indiana was esti- 

 mated at $2,000,000. Corn is the only food plant of the larva, 

 but the beetles are somewdiat more choice in food habits than 

 the Southern species. In the experience of the writer and 

 some others, they arc partial to thistle l)]ossoms, in which they 



Fig. 123-— Western corn root-worm. a. Beetle: h. larva, from side; c, leg of same; d, 

 pupa. All much enlarged; c, more enlarged- (Author's illustration, U. S- Dept. Agr ) 



deeply imbed themselves, to sunflower and goldenrod, and are 

 less frequently found on cucurbits. The beetles do some daiu- 

 age to corn by feeding on the pollen and gnawing the silk 

 and tassels, thus to a certain extent preventing cross-fertiliza- 

 tion and causing a partial blasting of ears. Other plants such 

 as ragweed and smart weed are frequented for the sake of 

 oollen. In late fall and early winter the beetles have the same 

 habit as the twelve-spotted and striped cucumber beetles of 

 gnawing into squash and pumpkin in the field. 



This species is evidently single-brooded. The beetles occur 

 in the field, like the Southern species, until November, in open 

 winters as late as the middle of December, which is, in the 

 writer's opinion, proof positive that the beetles hibernate, but 



