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experiments ... A. Numan arrived at the conclusion that agents 
endowed with great energy, and which arrive* in the stomach 
without undergoing any modification, act upon that viscus, but 
scarcely produce any effect on the larvas. No medication can 
therefore be recommended for their destruction or expulsion ! It is 
fortunate that their sojourn is only temporary, and that they are 
eliminated spontaneously when the summer returns. Therefore, 
as a cure should occur spontaneously, without any medication, 
there is no necessity to intervene unless the health is seriously 
compromised.” * 
Forest Fly; Spider Fly; Forester. Hippobosca equina, Linn. 
Hippobosca equina : 1 and 2, natural size, and magnified from life; 3, pupa 
removed from egg-like puparium (after Reaumur). Puparium, natural size and 
magnified, before complete coloration. 
The “Forest Fly,” or “New Forest” Fly as it is sometimes 
called, known also by the names of the “Spider Fly,” “Flat Fly,” 
and “Horse Louse” (scientifically the Hippobosca equina), has 
been a well-known pest to horses and cattle in the New Forest in 
Hampshire and its neighbourhood from at least as far back as the 
year 1781. As, however, it was generally considered only a local 
trouble, little attention was paid to it in this country beyond the 
area of the district in which it was mainly to be found, until the 
year 1895, when it was brought into more than ordinary notice by 
the New Forest (the especially known locality of the pest) having 
been selected as the scene of our autumn military manoeuvres. 
* ‘ Parasites and Parasitic Diseases of the Domesticated Animals,’ by 
L. G. Neumann; translated by Geo. Fleming, C.B., LL.D., &c., late Principal 
Veterinary Surgeon to the British Army, 1892. 
