320 Annals Entomological Society of America [Vol. IX, 



of eleven distinct segments, and is armed with setae. The head 

 is small and not well defined. The mouth-parts consist of two 

 external mouth-hooks, a median tooth and two fleshy lobes, the 

 latter functioning as attaching organs. There are two internal 

 pharyngeal plates. On the caudal segment is a second attaching 

 organ and four short spring-bristles; thus the larvae move about 

 by a looping movement or by jumping. Konig states that some 

 of the larvae were found attached to Podurans. 



The larva of a New Zealand species of Oncodes has been 

 figured and described by Maskell (13) in 1888. The larvae are 

 similar to those described by Konig. They differ from them, 

 however, in the following points: The body is made up of 

 twelve segments and the head is distinct. There are two mouth- 

 hooks and a fleshy lobe which functions as an attachment 

 organ. The caudal segment terminates in a point with three 

 spines. There are two stout spring bristles and the penultimate 

 segment has two spiracles. The larvae are said to walk in a 

 looping fashion. 



CONCLUSIONS. 



From the account herein presented, we may conclude that 

 the method of oviposition of Pterodontia flavipes is unique; 

 however, the potential reproductive power of the females seems 

 to be common with other members of the family, as is illustrated 

 by the observations of vStein (18), Konig (10) and Maskell (13). 

 It is undoubtedly one of the adaptations exacted by a parasitic 

 mode of life in which there is a large percentage of mortality 

 in the first larval stages. 



In general the activities of the newly hatched larvae of 

 Pterodontia are like those of Oncodes. However, morpholog- 

 ically, they are more highly specialized for their parasitic mode 

 of life, as is manifest by the lack of spiracles and by the presence 

 of elaborate scalelike plates on the body. 



BIBLIOGRAPHY. 



\. Aldrich, J. M. 1905. Catalogue of North American Diptera, Smithsonian 

 Inst., Washington. 



2. Brauer, Fredrich. 1869. Beitrag zur Biologie der Acroceriden, Verh. k. k. 



zool-botan. Gesel. Wien 19: 737-740; PI. 13, Figs. 1-6. 



3. Brauer, Fredrich. 1883. Die Zweiflugler Des Kaiserlichen Museums Zu Wien. 



Denk. Kais. Akad. Wiss. mathem-natur. Wien. 47: 61; PI. 5, Figs. 89-92. 



4. Emerton, J. H. 1890. An internal dipterous parasite of spiders, Psyche, 5: 404; 



two figs. 



