U. S. D. A., B. E. Tech. Ser. 23, Pt. II. Issued April 27, 1912. 



JMISCELLANEOirS PAPERS. 



AN INTERNAL PARASITE OF THYSANOPTERA. 



By H. M. Russell, 

 Entomological Assistant. 



INTRODUCTION. 



Although many of the injurious forms of thrips have been the 

 subject of exhaustive research, not only in the United States but 

 throughout the entire world, no internal parasites of importance 

 had been reared until 1911. In July the writer reared a parasite 

 from the prepupa of HeliotJinps fasciatus Pergande, which Mr, J. C. 

 Crawford has described under the name Thripodenus russelli. At 

 the present time the already-published literature on thrips para- 

 sites is not so abundant as to preclude a brief review in this paper. 

 In 1860 Mrs. Charlotte Taylor ^ described a parasite of thri])s on wheat 

 under the name Pezomachus thripites. This insect was figured and 

 described as a small wingless creature, a little larger than its host. 

 The thorax consisted of 2 nodes, while the antennae were made up of 

 40 joints and the palpi of 6. These parasites wei;e observed emerging 

 from thrips larvae in some numbers. They copulated in a short time, 

 after which the female deposited her eggs in the larvae of the thrips. 



Unfortunately this description is so meager that this insect could 

 hardly be recognized unless actually reared from its host again. It 

 represents, therefore, one of our lost species. 



In June, 1911, G. del Guercio published a short note on a chalcidid 

 parasite of Phl(Eothrips olex (Costa) Targioni. ^ He gave a short 

 description of the appearance of a parasitized thrips and an excel- 

 lent figure of the same. According to Del Guercio, the parasitic 

 larva seen within the host is of an oval shape, reddish in color, and 

 resembles a dipterous larva. The adult was mentioned only as "an 

 elegant chalcidid," which he stated he would describe, as soon as he 

 had enough specimens. Nothing was written concerning the biology, 

 habits, or relative abundance of this insect. 



Del Guercio, in September, 1911, published a further account of 

 this parasite of the olive thrips, to which he gave the name Tetrasti- 



American Agriculturist, vol. 19, p. 300, 1860. ' Rcdia, vol. S, pp. 65-63, 1911. 



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