1919] Platk: Bloodsucking Fly Larvae in Birds' Nests 199 



encountered in 1913, were found far distant from forests, and all of 

 them came from a height three to fifteen feet above the ground. 



Turning now to the effect which these blood-sucking larvae of 

 Protocalliphora azurea (Fallen) have on nestling birds, my observa- 

 tions seem to warrant the following conclusions: (1) from 5 to 10 per 

 cent of the parasitized nestlings die from loss of blood; (2) some of 

 the parasitized nestlings which do become full fledged are so weakened 

 by the loss of blood that they fall an easy prey to rapacious animals. 



Much remains to be done along this line of investigation in order 

 to determine how large and universal the damage is which is wrought 

 on our continent by this insect pest. Although the adults of both 

 Protocalliphora azurea (Fallen) and Protocalliphora chrysorrhea 

 (Meigen) are very rarely taken by collectors (see Henshaw, 1908, 

 p. 88, and Coutant, 1915, pp. 144, 145), my investigations show (hat 

 the former is not so rare, at least not in certain parts of the country. 

 So far, however, only forty-four bird's nests, infested by the larvae 

 of one or the other of these flies, have been recorded. All forty-four 

 of these infested nests were found at three places, one near Ithaca, 

 New York (Coutant, 1915), two at Wellesley Hills, Massachusetts 

 (Henshaw, 1908), and the remaining forty-one in the San Francisco 

 Bay region. It would be highly interesting, and perhaps beneficial 

 to our wild birds, if bird students in other parts of North America 

 as well as South America, would thoroughly investigate this matter 

 in their home districts. 



