19'20] Ferris — First Stage Larva of Cuterebra umericana {Fabr.) 13 



THE FIRST STAGE LARVA OF CUTEREBRA AMERICANA 

 (FABR.) (DIPTERA; OESTRID.E). 



By G. F. Ferris, 

 Stanford University, California, 



There appears to be but little information concerning the first 

 stage larvae of any species of Oestridse, the only very detailed figures 

 that I have seen being those given by Hadwen and Cameron^ of the 

 larvae of three species of Gastrophilus. I have been fortunate 

 enough to secure some notes on the first stage of Cuterebra ameri- 

 cana (Fabr.) (det. Aldrich) and present them in order that they 

 may not be lost, brief though they are. 



A female of this species was taken in flight at Palo Alto, Calif., 

 on October 8 and was confined in a glass jar. On this same day 

 (perhaps partially on the following) this female deposited from 100 

 to 150 eggs which were placed singly and were attached to the glass 

 by a glue so powerful that the eggs could not be detached without 

 being destroyed. Unfortunately no notes were kept as to the shape 

 of the eggs. 



The eggs began to hatch on October 22. In the case of the 

 species discussed by Hadwen and Cameron there has existed some 

 doubt as to whether the eggs hatch normally without the stimulus 

 of moisture, heat and friction, although these authors found that at 

 least a certain percentage do. In the case of Cuterebra americana 

 these factors seem to have no place as apparently all the eggs hatched. 



The first stage larvae are extremely active. Clinging to the 

 empty egg shells they waved the head energetically about in the 

 air and some of them deserted the egg shells and moved about, 

 progression being accomplished by means of a looping movement 

 much like that of a Geometrid caterpillar. No notes were kept 

 as to the length of time that the larvae lived without food. 



Descri'ption of the Larva. 



Length (flattened on slide) 1.4 mm.; body fusiform, tapering at 

 both ends (Fig. A) . Posterior extremity ending in a single flat lobe 



1 Hadwen, S. and Cameron, A. E. A Contribution to the Knowledge of the Bot-Flies, Gaa- 

 trophilus intestinalis DeG., G. hcemorrhoidalis L. and G. nasalis L. Bull. Ent. Res., vol. 9, pt. 2, 

 pp. 91-106, figs. (1918). 



