THE LEPIDOPTERA 



295 



If treatment is needed after the heads are half grown, they may 

 be dusted with pyrethrum, though the danger of poisoning them by the 

 use of arsenate of lead is practically none. 



A native cabbage butterfly closely resembling the last, was formerly 

 common in the North, but appears to have suffered from competition 

 with its imported rival. A southern native species has also become 

 somewhat reduced in abundance, but less so than the northern one. 



r 



FIG. 314. Male Sulfur or Yellow Butterfly (Eurymus philodice Godt.), natural size. 



(Original.} 



The common sulfur-yellow butterflies (Fig. 314) with more or less of black 

 markings on their wings are for the most part, feeders on clover in their larval 

 stages. One of them, the Alfalfa Caterpillar (Eurymus eurytheme Boisd.) is 

 frequently a pest on alfalfa. It occurs everywhere in the United States west of 



FIG. 315. Alfalfa Butterfly (Eurymus eurytheme Boisd.), about 



(From U. S. D. A. Bull. 124.) 



times natural size. 



the Allegheny Mountains and has been taken occasionally along the Atlantic 

 Coast, but is chiefly of importance in the Southwest. 



The adult (Fig. 315) spreads about two inches and its wings are orange- 

 yellow with black outer borders; a black spot in front of the center of the fore 

 wing and two reddish-orange spots which touch each other, near the center of 



