GASTEOPHILUS HAEMOEEHOIDALIS AND OTHER BOTS. 



Linnaeus, Fabricius, and De Geer occupied themselves with the 

 early classification, and not until 1797, with Bracy Clark, does the 

 natural history of the Oestridae truly commence. To this historical 

 work of Bracy Clark a few additions, many of which are cited in the 

 bibliography, have been made by subsequent writers. 



In conformity with the rules of nomenclature and following the 

 reestablishment of the Linnaean designation " intestinalis " by Guyot, 

 " Gastrophilus intestinalis " is given preference rather than " Gastro- 

 philus equi? 



Aside from priority, the specific name " equi " is not reliable, since 

 there are several spe- 

 cies of Gastrophilus 

 which infest the 

 horse; moreover "in- 

 testinalis " has been 

 adopted by a number 

 of dependable au- 

 thorities. 



SPECIES DIFFEREN- 

 TIATION. 



The eggs, larvae, 



and. adults are SO p IG ^ — Gastrophilus nasalis: Female. Oviposits com- 

 easily distinguishable monly under the jaws of horses. Greatly enlarged. 

 • xt | • .i ■. -. (Original.) 



in this genus that it 



does not require a study of detailed descriptions to enable a student 

 to determine the species. (Figs. 1, 2, 3.) Prof. Garman's key to the 

 wing venation, a reliable index to the species, is here quoted. 



Key to Wing Venation of Gastrophilus Spp. 



1. Discoidal cell not closed by a cross vein G. pecorum. 



Discoidal cell closed by a cross vein 2 



2. Wings marked with brown O. intestinalis. 



Wings not marked with brown 3 



3. Anterior basal cell nearly or quite equal to the discoidal cell in 



length G. nasalis. 



Anterior basal cell markedly shorter than the discoidal 



cell G. haemorrhoidalis. 



The cloudy wings of G. intestinalis and its habit of depositing 

 upon any convenient portion of the horse where it is not disturbed, 

 but most commonly on the forelegs, will enable one to distinguish 

 it most readily. 



G. nasalis is smaller than G. intestinalis, densely hairy, with the 

 thorax yellowish red or rust colored. Its most common place of 

 oviposition is under the jaws, but it is sometimes observed to oviposit 



