The Chalcis Flies 



dark yellow, but soon becomes black, especially on the head and 

 abdomen. In from three to eight days the adult parasite emerges. 

 Just think what a speedy development this means ! — two days 

 for the egg stage, three days for the larval stage, and three days 

 for the pupal stage — an entire generation in eight days. Even 

 the prolific and rapid-breeding house fly cannot beat this. It is 

 altogether the shortest development of any Hymenopterous para- 

 site that has been studied, and it is due to this great rapidity of 

 development of this parasite, together with the abundance of 

 certain other parasites, that the famous cotton caterpillar of the 

 South, an insect which used to damage the cotton crop annually 

 to the amount of fifteen millions of dollars, is periodical in its attacks 

 and while very abundant some years is very scarce in other years. 

 During the summer when Mr. Schwarz studied the species in 

 Central Alabama he found that there was an almost complete 

 destruction of the caterpillars in the early part of October, and that 

 this destruction was principally due to this parasite. 



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