THE CANADIAN ENTOMOLOGIST 39 



Specimens was a typical //. niiin'ro.slris cocoon containing an Hymenopterous 

 cocoon of a kind indistinguishable from that of Balhyplertes currulionis, para- 

 site of the Alfalfa Weevil introduced into Utah from P2urope. Later this parasite 

 was found in about 50 per cent, of the early cocoons of //. nigrirosir's at Puyallup, 

 Wash. In 1010 adults of this parasitic species were swept from clover at Forest 

 Grove on two occasions. The parasite was also found to be present at Nehalem 

 on the ocean front, where the wce\il larva? were not very easy to find. This 

 parasite has been determined by Mr. A. B. Gahan^ of the U. S. National Museum 

 as "Bathyplect-es exigua Gravenhorst, a European species hitherto not recorded 

 in the United States^ and apparently without host record in Europe." This 

 parasite, like other members of this European genus, is especially adapted to 

 prey upon the larvae of Hypera, the young larva; of which it searches out in 

 their concealed locations in the axilliary buds under the bracts on clover stems 

 or under the flowering heads of clover. Thus we have a highly specialized 

 larasite occurring even on the outskirts of the area infested by its host. 



In addition this parasite of //. nigrirostris larva?, a Pteromalid parasite 

 attacking the pupa; within the lacy cocoons was found in fair numbers during 

 the seasons of 1918 and 1919 at Puyallup, Wash., and Auburn, Wash. This 

 parasite also shows a special adaptation for parasitism of Hypera, within the 

 cocoons of which it occurs as naked larx'a; or pupa?. However, it is not an active 

 flier like B. exigua, and would probably spread more slowly than that species. 

 It has not yet been found on the outskirts of the infested area. This parasite 

 has been determined by Mr. A. B. Gahan as Dihrachoides dynastes Forster, a 

 European parasite of the Alfalfa Weevil, //. postica, introduced into Utah but 

 ne\er recovered there so far as known to the author. This genus also, accord- 

 ing to Mr. Gahan, was not represented in our fauna so far as known, previous 

 to its disco\ery in Washington. 



The occurrence in the Pacific Northwest of these parasites, apparently 

 foreign to our fauna and not as yet found in the east, where //. nigrirostris has 

 been known for many years and recently studied,^ suggests that the invasion of 

 the Pacific Northwest may be from a source different from that of eastern 

 America. It is unusual for highly specialized parasites of an introduced species 

 to become common so soon after the appearance of the host in a new region. 

 It has been shown that H. nigrirostris is spreading from the north to the south 

 in the Pacific Northwest. This seems to indicate that the species is really 

 circumpolar in its range, as Schwarz^ suggests, or that it has come from eastern 

 Siberia by natural dissemination or accidental introduction. In the latter case 

 the weevil was probably introduced by easy stages, such as would not eliminate 

 the parasites, into the northern part of the \ ancouveran faunal area of \'an 

 Dyke,^ which he considers includes e\'en the lower levels of the Aleutian Islands 

 and the southern margin of the Alaskan peninsula. 



4. My thanks are due Mr. A. B. Cahan for determinations of parasites and kind per- 

 mission to use extracts from his correspondence. 



5. Mr. A. B. Gahan informs me that a specimen determined by him as B. exigua was re- 

 cently reared from a larva of Hypera punctata at Mechanicsburg, Pa., by Mr. T. L. Guyton. 



6. Herrick, Glenn \V. and Deiwiler, J.D. "Notes on some little-known pests of red clover," 

 Tour, of Ec. Ent., Vol. 12, No. 2, 1919, p. 206. 



7. Schwarz, E. A., Proc. Ent. Soc. Wash., Vol. 9, 1908, p. 114. 



8. Van Dyke, Edwin C. Annals of the Ent. Soc. of America, Vol. 12, No. 1, 1919, p. 1. 



