476 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



but often sufficient means as hand-picking and trapping can be 

 effectually used, especially in smaller gardens. Clean cultiva- 

 tion and the destroying of all hiding, places for over- wintering 

 insects are great helps in the struggle. 



Various special remedies are described in the accounts, which 

 follow, of a few of the more important of the garden truck 

 pests. 



POTATOES 



The Colorado Potato -beetle (Leptinotarsa decemlineata). 

 This beetle is in many regions the best known of all the garden 

 pests. Its black and yellowish striped wings make it a 



FIG. 226. Colorado potato-beetle, Leptinotarsa decemlineata, and its 

 larva. (About twice natural size.) 



conspicuous object on the vines, and the results of its work are 

 all too evident. It furnishes a good example of the way in 

 which an insect once regarded as harmless may, by a slight 

 change in its habits, become of very great economic im- 

 portance. Originally it fed on various common weeds, es- 

 pecially the Colorado thistle, Solanum rostratum, in Colorado 

 and other Rocky Mountain states. When potatoes (another 

 species of Solanum) began to be planted in the region where 

 the beetle occurred it found them more to its liking, and with 

 the abundance of food that could be had with little or no effort, 

 it so increased in numbers and spread so rapidly that it soon 



