GENERAL CROP PESTS 63 



spotted cucumber beetle (fig. 3), the parent of the southern 

 corn root-worm. It will be considered more at length in the 

 chapter on corn insects. 



FLEA-BEETLES 



Flea-beetles (Halticini) constitute a sub-family of the leaf- 

 beetles. They are of elongate oval form and similar color, 

 frequently striped like the cucumber beetle, and may be dis- 

 tinguished by their enormously developed hind thighs, which 

 furnish them with powerful leaping ability. The most injurious 

 forms are minute and dark-colored. Their habit of suddenly 

 hopping from the vegetable on which they are feeding has given 

 them the common name of flea-beetles or fleas, some species 

 being known as "potato flea," "cabbage flea," etc., according to 

 the plant infested. Many flea-beetles are general feeders, and 

 nearly all are subject to a periodicity, dependent on factors with 

 which we are little acquainted, but doubtless in large part 

 traceable to atmospheric conditions, moist weather furnishing 

 the best conditions for the development of the young or larvae, 

 and dry weather being inimical to their increase, this hypothesis 

 being based upon the knowledge that the larvae of many species 

 are subterranean. 



Injury is frequently very severe on young plants and is due 

 in the greatest measure to the ravages of the adult flea-beetles 

 which frequently appear in prodigious numbers in cultivated 

 fields and like a pestilence sweep everything before them, their 

 depredations often necessitating the replanting of entire crops. 



The larvae of most flea-beetles develop in weeds, a compara- 

 tively small proportion living on cultivated crops. Knowledge 

 of this fact is of value in indicating methods of control. 



The Pale-striped Flea-beetle (Systcna blanda Mels.) is a de- 

 structive vegetable-feeding species. It measures about an 

 eighth of an inch, is cream-colored, with nearly black abdomen 

 and eyes, and the wing-covers are ornamented with a bright 

 sutural and two narrower marginal stripes of dull light brown 

 (fig. 34, h). The larva is white and slender, with light brownish- 



