60 FIRST REPORT ON ECONOMIC BIOLOGY. 



be transferred in this manner I have not sufficient evidence to show. 



In the horse they generally attack the mane and neck, and the 

 root of the tail, whereas the allied species of the ox (H. eurysternus 

 (Nitzsch), and H. vituli (Linn.) attack the head, back and loins as well. 



Thorough cleansing of the skin of all animals attacked 

 is essential. Where poisonous dips are used care should be taken not 

 to dress too large a surface at once, and not to use the fluid too strong. 



When badly attacked, closely clipping the hair is advisable, and 

 treating with a i to 5 per cent, aqueous solution of creolin, giving a 

 second application five or six days later. 



SOME OBSERVATIONS ON THE EGGS OF THE 

 HORSE BOT FLY. 



Gastrophilus equi (Fabr). 



Although there is a voluminous literature treating of the structure 

 and life-history of the Horse Bot Fly, Gastrophilus equi (Fabr.), I have 

 been unable to find a single correct figure of the egg of this insect. 



Many authors do not figure it at all, whilst those that do, repre- 

 sent it in an incorrect manner. 



The most recent description I know of is that by Froggatt, 1 who 

 states : " The eggs are dull light-brown to dirty white in colour, 

 elongate oval in form, somewhat pointed, and broadest at the apex." 

 His figures (Figs. 3 and 4) show a somewhat spindle-shaped egg, with 

 strong longitudinal striation and an operculum lying at the right 

 angle to the long axis of the egg, and with the broad end uppermost. 



Osborn 2 states : " They are about one-sixteenth of an inch in 

 length, and taper a little towards each end, though the attached end is 

 the smaller. The outer end is provided with a little cap (operculum), 

 which is set quite obliquely to the axis of the egg, though some authors 

 represent it as cutting the egg square off at the end." 



Osborn's figures (Figs. 37 a and b) are both upside down. 



Neumann's 3 account reads as follows : " The ova of the Castro- 



* Reprinted from the Journ. Econ. Biol., 1910, vol. v, pp. 9 17. 



1 N.S.W. Dept. of Agric., Miscell. Pub., No. 432, March, 1908, p. 3. 



2 U.S. Dept. Agric., Div. of Entom., Bull. No. 5, new series, 1896, p. 79. 



3 A Treatise on the Parasitic Diseases of the Domesticated Animals. English Trans., 2nd ed., 

 1905, p. 293. 



