304 MEDICAL ENTOMOLOGY 



are put into the tray they will soon disappear, for as noted above tabanid 

 larvae are fond of eating their own kind. The mud should first be 

 mixed with water and then passed through a sieve, and in this way all 

 large larvae will be removed. 



The tray described above can be readily converted into a cage of any 

 height by making a framework of stout wire, which is soldered at intervals 

 to the outer sides. Mosquito netting is then fitted over this and tied 

 securely round the bottom (Plate XLIV, fig. 3). The cage should be placed 

 on a table, the legs of which are standing in large tins of water ; it is 

 well to place the table away from the wall, and if possible in an eastern 

 situation so that it gets a few hours of sunlight in the morning. Great 

 care should be taken to see that the net is properly secured round the 

 bottom of the tray ; spiders will find their way into the cage, and it is 

 more than annoying to find a special fly in the clutches of one of these 

 creatures. For the smaller species of tabanid such a large tray is un- 

 necessary, and a piece of galvanized iron seven feet long will make two 

 smaller cages (Plate XLIV, figs. 1 and 4). 



These cages are suitable not only for breeding tabnnids, but also 

 for keeping muscids in captivity and for feeding experiments with 

 mosquitoes. Tabanids may be kept alive in these cages for at least 

 three weeks if they are regularly fed. 



If caught specimens of tabanids are placed in suitable cages, it will be 

 found that many of them will lay their eggs, especially if they are taken 

 out in large test tubes every three or four days and fed on some 

 animal, preferably a cow. 



When an egg mass has been obtained the object on which it is fixed 

 should be taken to the laboratory and placed in a small dish of water, 

 carefully protecting it from the attacks of ants. As soon as the larvae 

 hatch out they should be transferred to one of the trays prepared as 

 described above. They should on no account be picked up with forceps, 

 but drawn up into a glass pipette of suitable bore ; in this way they can 

 be easily counted. About fifty at most should be placed in each tray, as 

 if they are well scattered there is less chance of their destroying each 

 other. If the water contains weeds and surface plants, the young larvae 

 will find small crustaceans and similar forms of life on which to feed ; 

 later the tray should be well stocked with earth worms of all sizes, the 

 smaller ones being very suitable for the young larvae. 



The great advantage of rearing the larvae in these trays is that they 

 require little or no attention except the regular changing of the water, 

 the addition of fresh earth worms about every ten days, and the removal 



