RELATION TO THE FARMER 



253 



pean countries are not unduly favorable to its rapid 

 multiplication. Their vines are simply not used to the 

 attack and sink under it. 



So on the other hand, we have a long list of insects 

 in North America introduced from foreign lands. The 

 Hessian fly, the cabbage butterfly, the asparagus beetles, 

 the elm-leaf beetle, the cottony cushion scale, the black 

 scale and the San Jose scale, are only a few of the 

 well-known pests that have been with us for some time. 



FIG. 116. Vedalia cardinalis, the destroyer of the cottony cushion scale: 

 b, larva; c, pupa; d, adult. 



Most of our troublesome forms have come to us across 

 the Atlantic: the cottony cushion, black and San Jose 

 scales came to us across the Pacific. The former never 

 got away from the western coast ; the latter has covered 

 the entire country and has become the most generally 

 troublesome pest of the horticultural industry. The 

 cottony cushion scale was eliminated by a brilliantly 

 successful experiment, resulting in the introduction of 

 the specific check to the species from its native home. 

 It was an experiment that we can duplicate at any time 

 with the same factors. It is quite a different matter to 

 import parasites and predatory forms hap-hazard to 



