164 



and control, and it is conclusively shown that larvae that bore in at 

 the hock reach the back and become mature there. It has, however, 

 been impossible to trace the course of migration through the skin to 

 the wall of the gullet, where the maggots in the second stage are 

 found embedded in the submucous coat from October to February ; 

 evidence tends to show that the maggot works through the tissues 

 not far beneath the skin until it reaches the neck, when it goes deeper 

 and penetrates the gullet wall from outside. The pupal period varied 

 from 46 to 32 days, becoming appreciably shorter as the season 

 advanced. Five larval stages are mentioned [cf. R.A.E., B, ix, 171 ; 

 X, 135]. 



Many attempts have been made to find some ointment or wash that 

 would be fatal to the maggots on contact and yet harmless to cattle. 

 In the earlier report various nicotine dressings are mentioned that 

 killed 20 to 60 per cent, of the maggots, but in some cases injured the 

 skin. A dressing containing 1 per cent, nicotine proved highly 

 effective, but was very injurious and had to be discarded. The most 

 promising dressing is made of Corry's tobacco powder and lime-wash, 

 by mixing 1 lb. of fresh quick-lime with a gallon of water and steeping 

 3-4 lb. of tobacco powder in the lime-water for 24 hours and then 

 straining through coarse muslin. The liquid should be applied with 

 a cloth or brush to the backs of cattle ; it must come into actual contact 

 with the maggots, and the treatment should be repeated at least 

 four times from February to the end of May. Nicotine (0"5 per cent.) 

 in pure solution proved less effective than in the above mixture. 

 The injection of various substances into warbles in the backs of cattle 

 was tried and killed a fairly high percentage, as the injection brings 

 the fluid into direct contact with the insect. Salt and glycerine 

 (saturated) killed 68| per cent. ; tincture of iodine, 67 ; tannic acid 

 (10 per cent, in alcohol) 63; and copper sulphate (7 per cent.) 61. 

 Copper sulphate solution of the same strength as injected was used 

 as a wash and killed only 15 to 30 per cent., and iodine tincture rubbed 

 on killed 32 per cent. The objection to the general use of injections 

 is their difficulty in ordinary farm practice. Sulphur-dioxide gas 

 applied under pressure to each warble has previously been found to 

 kill 93 per cent, of the maggots. No other application approaches 

 this method in its effects, but the difficulties of applying it on a large 

 scale seem to preclude its use. This and other gases liberated under 

 impermeable covers spread over the animals' backs gave much poorer 

 results, the best being 66i per cent, killed by chlorine. 



Further trials have been made with preventive dressings, but none 

 gives any promise of success. Corry's " Fly Lotion " gave a slight 

 relative protection to calves when used on the legs ; birch-tar dressings 

 also had some effect, but the stiff and sticky nature of this substance 

 renders its use very difficult and unpleasant. Injections with arrhenal 

 seemed to have no effect. 



LouGHNAN (W. F. M.). Notes on a Case of Myiasis.—//. R.A.M.C, 

 London, xxxviii, no. 6, June 1922, p. 458. 



A case of myiasis due to the larvae of Dermatobia hominis, L. 

 {cyaniventris, Macq.) is recorded from British Honduras. The lesions 

 occurred immediately behind the external ankle bone of either foot. 



Although the eggs have been stated to be laid direct on the skin 

 of man and domestic animals, it is probable that they are normally 

 laid in membrane-like cases on damp leaves. The membrane is 



