JOURNAL 



OF 



ECONOMIC ENTOMOLOGY 



OFFICIAL ORGAN AMERICAN ASSOCIATION OF ECONOMIC ENTOMOLOGISTS 



Vol. 5 DECEMBER, 1912 No. 6 



NOTES ON THE BIOLOGY OF CHELONUS TEXANUS CRESS' 



By W. DwiGHT Pierce and T. E. Holloway, Bureau of Enloninlogy, ['. S. 

 Department of Agriculture 



In this paper we describe the very pecuHar life-history^ of Chelonus 

 texanus Cresson. In brief the adult Chelonus deposits its eggs in 

 the eggs of its hosts but the parasite emerges not from the egg, but 

 from the larva developed therefrom. Oviposition in the host's egg 

 and retarded development of the parasite to permit the host to hatch 

 and grow to considerable size has been pointed out by Marchal (Sum- 

 marized by Bugnion, 1907. Smithsonian Report for 1906. pp. 310- 

 314) with reference to the Encyrtus fuscicollis Dalman which oviposits 

 in the eggs of Hyponomeuta malinella, etc., and by Silvestri (Biologia 

 del Litomastix truncatellus (Dalm.). Portici, pp. 4, 5, 10. 1906) with 

 reference to Litomastix truncatellus Dalman which oviposits in the 

 eggs of Plusia gamma Linnaeus and other Lepidoptera. Litomastix 

 truncatellus is polyembryonic and possibly psedogenetic in alternate 

 generations; Encyrtus fuscicollis is also polyembryonic, but the Chel- 

 onus we have observed is a single and simple parasite. The Lito- 

 mastix adult measures only 1.9 mm. in length and the egg of Plusia 

 measures 0.6 mm. in diameter. Chelonus measures fully 5 mm. and 

 the eggs of Heliothis measure about 0.5 mm. in diameter, while those 

 of Laphygma are still smaller. Thus the contrast is much more strik- 

 ing when one observes Chelonus ovipositing than it would be in observ- 

 ing Litomastix. 



1 Published by permission of the Chief of the Bureau of Entomologj-. 



2 It appears since sending in the above manuscript that during the summer of 

 1912 Mr. R. A. Vickery, of the Bureau of Entomologj', at Brownsville, Texas, 

 confirmed these observations in regard to Chelonus and Laphygma. It alvo ap- 

 pears that Mv. T. H. Parks, also of the Bureau of Entomologj', reared Chelonus 

 from Laphygma thi-ough two generations at Greenwood, Miss., confiiming in all 

 respects the observations reported by Mr. Pierce in the above article. 



