198 DRONE-FLIES. 



brush it off with a feather, when I saw, rather to 

 my surprise, that the flies were greedily devouring 

 the pollen grains, brushing them off their downy 

 bodies by means of the combs on their fore-legs, 

 and then the flaps at the end of the proboscis 

 rapidly picked up each grain until there was not 

 one left. I am glad to know this fact about their 

 diet, as I can now give the interesting pets both 

 liquid and solid food, which will no doubt help 

 to maintain them in health and vigour. 



We will now turn to the larvae stage of these 

 flies when, as purifiers of the foulest putridity, 

 they are doing us most essential service. The fly 

 lays its eggs in the mud of some stagnant 

 ditch, and out of each of them emerges a whitish 

 worm-like grub with a long tail, which is its 

 breathing apparatus, and must therefore always 

 reach to the surface of the water. . It is formed 

 of graduated tubes, which can be retracted or 

 drawn out exactly like a telescope. If the water 

 is shallow, only one or two tubes are needed, and 

 the tail appears somewhat thick, but if, owing 

 perhaps to a sudden shower, the water deepens, 

 then the creature can draw out tube after tube 



