SOME PARASITES OF SIMULIUM LARV.E. 



adult organs, without affecting the larval organs to any great 

 extent, except in so far as they are kept well supplied with 

 alkaline fluids and'are thus capable of developing to their utmo-t 

 extent. This would account for the somewhat larger size of 

 parasitized individuals. 



It may he. however, that the Mcrmis doe- not actually secrete 

 an alkaline -ill -lance, hut brin-- ahi'in an increased alkalinity 

 in the hodv of it- h-.-i by ah-orhini; whatever arid- are lonned 

 in it. The prohahility of this being the true condition i- in- 

 1 hy the fact that closely related \\orm- li\ e in acid media. 

 Midi as \int-var or sour paste (An'^nillnln nccti Chrb-. . \\liich 

 uould point to the fact that the worm require-, and ah-orhs, 

 acids 'liriir^ its development. In either case the eliect on the 

 ho-t \\ould he the same in that there is a reduction in the acii\ iiv 

 of the arid- \\hich ap[)ears to be essential to tin- d.-\rlopineiii ,-t 

 the hi-iohla-i- Whether this. is the true explanaiion or not, 

 it i- it-nail) that the presence of the worm does ha\e a direct 

 inliihiioiA .11.. t upon the development of the ima^inal organs, 

 hni does not ha\e a similar effect on the lar\al tissm 



A -uppre--ioti of pupal and adult organ- \\ill natnrallv he o| 

 advantage to the parasite for two reasons: 



1. \onii-hment is not required for building up the-e ti ue- 

 and then lore more \\ill he available in the \\\ cavity o| 

 the ho-t. 



2. The maturity of the host will be deferred ilui- ^ivin;^ the 

 para-ite a longer life, should it require extra time for develop- 

 ment. In mo-t of the observed cases, ho\\e\er. the \\orm killed 

 it- ho-i, h\ emerging before or at about the -ame time that the 

 uninle-ted latxa- \\ere pupating. 



A -imilar though le-- marked case of metal heieK due to para- 

 ^iti-m h\ Mt-ntii* ha- been described and h.^iind h\ Mia/ek 'OM 

 in the queen- of a Kniopean ant (Lasius alienus I. In ihi- case the 

 para-iti/ed lar\a- matured and produced adult ant- \\hirh were 

 noiniil in all external characters with tl:< piioii of a -real 



reduction in the -i/e of the wings. Through the kindne-s of 

 I'roU- or Wheeler 1 ha\e been able to examine some -imilarly 

 para-ili/cd -|)ecimen- of a closely relat.-d American SpCClCS 

 /.,;.v//(.v ;/<v)?//^cn in order to see whetlu-r the de\ <-lo|unent of the 



