52 BULLETIN 173, U. S. DEPARTMENT OF AGRICULTURE. 



cally all the attempts to control the thrips by artificial means have 

 been within the United States. Of the few natural enemies of Thy- 

 sanoptera that do exist, the most important seems to be Triphleps 

 insidiosus Say, which feeds upon thrips by impaling them upon its 

 beak and sucking out the juices. Megilla maculata De G., chrysopid 

 larvae, and syrphid larvae have also been found feeding upon thrips. 

 Uzel * has found Triphleps minutus L. preying on thrips and credits 

 Heeger with the finding of Scymnus ater Kug., Gyrophaena manca Er., 

 and some fly larvae feeding in the same manner. Hinds 2 mentions 

 having found some small scarlet acarid attached to the membranous 

 area of the body of Anaphoihrips striatus Osborn. Uzel 1 and Quaint- 

 ance 3 have both found eggs of nematode worms within the bodies of 

 adult thrips. J. C. Crawford 4 in December, 1911, gives a short account 

 of Thripoctenus russelli Crawford, a new internal parasite of Thy- 

 sanoptera and later Russell 5 publishes a more complete account of the 

 life history and habits of this parasite. The first recorded host of T. 

 russelli was Heliothrips fasciatus Pergande, but it has been reared from 

 Thrips tabaci Lind. and Frankliniella tritici Fitch. Its oviposition 

 has been observed in Heliothrips femoralis Reuter and H. haemor- 

 rhoidalis Bouche. Great hopes were entertained by Mr. Russell for 

 its colonization among related injurious Thysanoptera. 



Of plant parasites, Thaxter 6 has taken an Empusa fungus destroy- 

 ing a species of thrips in the larval, adult, and pupal stages, and 

 Petit 7 and Hinds 8 have found a fungus which they thought was 

 causing some of the species of thrips to die. 



No effective natural enemy has been found preying upon the 

 pear thrips. Moulton 9 mentions some raphidians feeding upon the 

 younger forms of this species and has also found a species of ant 

 killing individuals. He mentions 10 a fungus which he regarded as 

 parasitic during the season of 1905 and 1906, but the last three or 

 four years have failed to show that any appreciable amount of 

 benefit has been derived from it. Very little of the fungus has been 

 observed during the years 1908, 1909, and 1910. 



1 Uzel, Heinrich. Monographie der Ordnung Thysanoptera. Koniggratz, 1895, 472 p. 10 pi. See p. 362. 



2 Hinds, W. E. Contribution to a Monograph of the Insects of the Order Thysanoptera Inhabiting 

 North America. In Proc. IT. S. N. Mus., vol. 26, p. 119, 1902. 



3 Quaintance, A. L. The Strawberry Thrips and the Onion Thrips. Fla. Agr. Exp. Sta., Bui. 46, 

 p. 79-114, 12 figs. July, 1898. 



4 Crawford, J. C. Two new Hymenoptera. In Proc. EmVSoc. Wash., v. 13, no. 4, p. 233-234, 1911. 



5 Russell, H. M. An Internal Parasite of Thysanoptera [ Thripoctenus russelli]. U. S. Dept. Agr., 

 Bur. Ent., Tech. Ser. no. 23, pt. 2, p. 25-52, figs. 11, Apr. 27, 1912. 



6 Thaxter, Roland. The Entomophthoreae of the United States. In Mem. Boston Soc. Nat. Hist., 

 v. 4, no. 6, p. 134-201, pis. 14-21, Apr., 1888. See p. 151, 172, 174, pi. xvii, figs. 200-219. 



7 Pettit, Rufus H. Some Insects of the Year 1898. Mich. State Agr. Coll. Exp. Sta., Bui. 175, p. 341-373, 

 20 figs, July, 1899. See p. 343-345, figs. 1, 2. 



6 Loc. cit. 



9 Moulton, Dudley. The Pear Thrips (Euthrips pyri Daniel). U. S. Dept. Agr., Bur. Ent., Bui. 68, 

 pt. 1, rev., p. 14, Sept. 20, 1909. 



10 Op. cit., p. 15. 



o 



