LAMP GLASS FOR COLLECTING SMALL DIPTERA 413 



on hot days. Larger tubes are useful for catching flies without the aid 

 of a net ; the large test tubes used in laboratories for cultivating bacteria 

 on potatoes are very suitable for this purpose. . 



To catch a fly when it settles on the skin of a host, stand near it for a 

 minute or so till it becomes accustomed to your presence. Then slowly 

 approach it with a large tube, and hold this over it for a few seconds at 

 a distance of a foot or so, till the fly gets accustomed to it. Then bring 

 it very slowly nearer, till within striking distance, and then put the 

 mouth of the tube over the fly as rapidly as possible. If this fails, 

 use the net, whisking it over the fly with a rapid turn. It is as a 

 rule unnecessary to touch the skin of the animal, for the fly is caught as 

 it rises. Hippobosca is sometimes difficult to catch, and in this case it is 

 best to have an assistant standing on the other side of the animal ; 

 the fly is thus kept moving from place to place and can then usually 

 be caught with the hand or a net. 



TEXT FIGURE i 



Colonel Adie, I. M.S., recommends the following simple method of 

 catching mosquitoes ; it is equally applicable in the case of other small 

 flies. An ordinary long test tube is taken, and either three holes are 

 drilled in it with a writing diamond, or the tube is drawn out in a blow- 

 pipe flame to a small bore, just too small to allow the fly to escape. The 

 flies are caught in the ordinary way by placing the mouth of the tube 

 over them, and are then transferred to a lamp chimney (Text fig. 1), the 

 broad end of which is closed with a piece of muslin with a fine mesh, 

 the narrow end by a piece of rubber tubing from an old bicycle 

 tyre, in which a central slit is made. When the mosquito or other small 

 fly is caught in the test tube, the mouth is thrust through the slit, and 

 the fly blown through into the chimney by placing the mouth over 

 the pierced or drawn out end ; the opening in the rubber closes automatic- 

 ally when the mouth of the tube is withdrawn. In this way a large 

 number of flies can be collected with the minimum amount of apparatus 



