28 BULLETIN 124, U. S. DEPARTMENT OF AGRICULTURE. 



level and having an average annual rainfall of probably less than 

 2 inches, while the Salt River Valley has an elevation of some 1,200 

 feet and an annual rainfall of about 8 inches. A study of the out- 

 breaks of Eurymus in the two vallej^s shows them to vary inversely 

 with the rainfall. In the dryer Imperial Valley the outbreaks are 

 more numerous and severe and the resultant damage is greater than 

 in the Salt Ri\ T er Valley with its greater rainfall and its longer 

 period of humid weather during the hot summer months. 



The worms when first attacked take on a lighter green color and 

 become sluggish; but in a few hours they change to a brownish 

 black and melt down into a decaying mass. A first sign of the 

 breaking down of tissues may often be noted when the worm is still 

 active, a slight exudation at some small broken place, usually in 

 front ; and the writer has noted specimens with the anterior end 

 blackened and the posterior end still slightly moving, showing that 

 life was not yet extinct. The attack upon a pupa is similar, except 

 that the stronger pupal covering usually prevents the melting down 

 of the specimen, and later the decayed contents of the interior dry 

 up, leaving the empty black shell still intact. 



BIRDS AND DOMESTIC FOWLS. 



Few records are available showing the relation of wild birds to 

 the alfalfa caterpillar. Several times the writer has observed birds 

 with larvse in their bills, but he was unable to capture these, not 

 having the necessary firearms. Domestic fowls, however, play an 

 important part in the history of this insect. In alfalfa adjoining 

 farmhouses where chickens or turkej^s have the run of the field one 

 rarely finds alfalfa caterpillars in numbers, whereas fields adjoining 

 chicken lots inclosed with wire fence, keeping the poultry out of the 

 alfalfa, suffered severe damage. In Mr. R. N. Wilson's notes for 

 1912 he reports that " Mr. Carlos Stannard, living 4 miles northeast 

 of Glendale, Ariz., killed a young rooster and found 24 Eurymus 

 larvse in the rooster's crop." Mr. T. Scott Wilson was informed by 

 Mr. Everett, living near Tempe, that he and his wife had found a 

 dozen larvas in a chicken's crop, the chickens having access to an al- 

 falfa field growing near the house. By the same observers, turkeys 

 have been noted feeding greedily upon the larvse, a flock in travel- 

 ing across an alfalfa field eating hundreds of them. Mr. T. Scott 

 Wilson, on July 21, 1913, at Chandler, Ariz., made the following 

 note: 



I observed one dozen turkeys in a half acre of alfalfa on the lots of the 

 United States power house feeding upon Eurymus larvse. The alfalfa 

 is about 12 inches high and is tender. I find only a few Eurymus feeding 

 upon this alfalfa, while in a large held just across the fence the alfalfa is 

 almost destroyed, except that in that portion next to the house where the tur- 



