45 BtTLLEIIX 597, U. 5. DEPABTMENT OF AGBICTJMUEE. 



deposited eggs it would probably prevent development of the embryo. 

 as is the case with hens' eggs during incubation: but even a test of 

 this kind was only slightly effective. 



A 2 per cent nicotine-sulphate solution was only partially effective. 

 Nitrobenzine gas. which has recently been brought to our attention 

 as a funiigant for external parasites of animals by Prof. "William 

 Moore, of the University of Minnesota, yielded good results at 25= 

 •24:. and 10 hours' exposure, but only a small percentage was killed 

 at 4 hours. The firmigation was conducted in a common glass fruit 

 jar into which a strip of cloth, impregnated with a few drops of 

 nitrobenzine. was suspended. 



The phenol compounds, by a contact application, seem to be most 

 effective in destroying young larva? and preventing the further de- 

 velopment of embryos. It will be observed that carbolic acid con- 

 taining 2 per sent phenol yielded as good results as higher per- 

 centages, and that this substance was most effectively used. 



With carbolic acid as a wash it will be well to be cautious of its 

 effects upon the hands. If used at too great strength, the exposed 

 skin of the hand will become white and peel off. although it does 

 not affect the skin of the horse, which is protected by the hair. 



SUMMARY. 



Three species of horse bots — the common bot-fly (G astro phUus 

 mte " U . the throat bot-fly { G. nasal is ) . and the nose fly ( G. hae- 

 morrhoidalis) — occur in the United States, and each is a source of 



considerable injury to horses. This injury is produced through 

 worriment caused by the flies at the time the eggs are laid and by the 

 attachment of the larva?, or bots. in the alimentary tract. 



tropMlus ' testm dis and G. nasaZis are widely distributed in 

 the United States but G. haemor-rhoidali? is confined to the Xorth- 

 Central and northern Eoeky Mountain States. 



The nose fly \ G. aaemo/Thoidal's) is by far the most annoying to 

 horses at the time its eggs are laid. The adults appear early in June 

 and reach the maximum of abundance during the first half of the 

 season, disappearing with killing frosts. The eggs are deposited on the 

 minute hairs on the iips. and those near the edges which are kept moist 

 and receive friction hatch in from 5 to 10 days. The larva? are taken 

 in with food or water and attach themselves to the walls of the 

 stomach. Here they remain until the following winter or spring 

 I then migrate to the rectum, where they reattach. Before leaving 

 the host they usually attach close to the anus and protrude from it. 

 They remain in this position from 40 to 71 hours. After dropping 

 ad tl 5 bots -eek protection and pupate in from IS to 170 

 hours later. The pupa stage lasts from 21 to OS days. The adults are 



