Reports to the Board of A griculture. 127 
both are apparently European. It may be, however, that H. lineata 
is natural to both Continents.” 
The differences between the two species are pointed out later. 
The life-history of H. bovis is, I feel sure, not completely known, 
but that of H. lineata is, and it is probable that the various phases 
of development are the same in both species. 
The (Estridss to which the Warble Elies belong are two-winged 
Hies or Diptera, which are all parasitic in their larval stage upon and 
within mammals ( H . lineata, CE. ovis, G. equi, etc.) and man 
{D. noxialis). 
Damage caused by Ox Warbles. 
The damage caused by these pests is due both to the imagines or 
adult hies and to their larvae or “ bots.” The hies, by frightening 
stock when on the wing and on the look out for a host on which to 
deposit their eggs, frequently cause loss amongst “ in-calf ” cows by 
making them stampede about the fields, as also in other ways. 
The maggots or “ bots ” living beneath the skin perforate the 
hide, and so ruin it when present, as they often are, in considerable 
numbers. They also cause loss to the butcher, who often finds the 
flesh beneath the “ warbled ” areas so altered by the inflammation 
set up by the parasites that the beef in that region is spoiled. This 
so-called “ licked beef” has a straw-coloured, jelly-like appearance 
in a newly-slaughtered carcase, but it turns to a dirty green in a 
few hours. 
Lastly the farmer and grazier may suffer direct loss by the actual 
death of the affected stock, from inflammation set up by the parasites 
when present in large numbers. 
Life-history of H. lineata. 
The life-history of this species is now well known. 
The fly deposits her eggs upon the hair of the beast, particularly 
on the legs, just above the hoofs, hence a common name for this fly 
in America, the " heel-fly,” but they are also placed elsewhere. The 
eggs are fastened to the hairs, usually several together. The egg 
is of a peculiar shape (fig. 22, c), and is about one-twelfth of an inch 
long ; each egg immediately it is laid by the female is firmly attached 
to the hair by a process which clasps the hair. The animal licks 
the place where these eggs are placed, and the larvae hatched from 
them are carried by the tongue into the mouth. 
The maggots pass into the gullet or oesophagus and soon penetrate 
its walls ; then they moult their skins, become smooth, and wander 
