THE BUTTEHFLY 



39 



Economics. — The IjCi^icIoptera in general are very de- 

 structive to vegetation. In the review of the different families 

 that follow there will be found an account of some of the more 

 important economic species. Unfortunately we have in this 

 country not only an abundance of injurious native species, 



Fig. 39. — A " aylvan scene . . . 



Where shadows dark and sunlight sheen^ 

 Alternate come and go." 



but many exotic forms that have been imported. When these 

 forms were removed from their natural enemies their fecundity 

 was left unchecked, and the result has been that thej^ have 

 brought great devastation on vast agricultural districts. The 

 earnest attempt of a state to keep down for a while an intro- 

 duced pest, even at great expense, is commendable. Among 

 the useful Lepidoptera are the silkworms, of which the most 

 important l^elong to a single family (Bombycidis) described 

 below. 



