412 THE CANADIAN ENTOMOLOGIST. 



5. ornatum by Leger ('97), and another from a Brazilian ? species by 

 Luta and Splendore ('04 and '08). Lutz ('09) also records the 

 presence of a nemathelminth in BraziHan Simuliida?. 



The parasites found in Simuliid larva^ around Boston during 

 1911 may be summarized as follows: 



1 . Parasites of the Spring brood of Simulium. 



Various Myxosporidia spp. up to 80% mortality. 

 Mermis sp. up to 25% mortality. 



2. Parasites of the Fall brood of Simulium. 



Glugeaspp. up to 10% mortality. 

 Gregarine sp. up to 50% mortality. 



No experiments have been made upon the possibility of trans- 

 ferring these parasites from one species of Simulium to another, but 

 so far as can be seen there should be no great difficulty in ac- 

 complishing this, for in all. cases observed the parasites infected all 

 species of larvae present at the same time in the streams where the 

 former occurred. There is, however, a seasonal variation of para- 

 sitism, for the species taken in the spring were not found in the 

 fall, so that it is probable that only those species of Simulium 

 whose life history coincides with parasitised species could be in- 

 fected with the parasites of the latter. 



Explanation of Plate XV. 



Fig. 1. Mermis parasites in situ. 



Fig. 2. A, normal histoblasts of mature larva. B, histoblasts 

 of full-grown larva containing Mermis, sp.; r f, respiratory fila- 

 ment histoblast; w% wing histoblast; h, halteres histoblast ; 

 1 (1, 2, 3), leg histoblasts. 



Fig. 3. Glugeid parasite in situ. 



Fig.. 4. Gregarine in situ. 



Literature Cited. 



Hagen, H. a.— '72. Stettin ent. Zeit., pp. 392-393. 

 Heymons, R. — '96. Sitzungsber. d; Ges. nat. Fr. Berlin. 

 KOLBE, H. J.— '03. Allgem. Zeitsch. fur. Ent., Bull. 8, No. 1 

 28. 



