DIPTEEA. 41 



know that there are six. Reaumur, as also Leuwenhoek, thought 



he saw two in the form of a sword blade with three edges. These 



have the points reversed, and are serrated on the convex side of 



the bend (Fig. 25). To form an idea of the shape of the other 



points, the reader should look at Figs. 26 and 27. He will then 



see that the gnat's sting is a sword in miniature. 



The prick made by so fine a point as that of the sting of the 



gnat, ought not to cause any pain. " The point of the finest 



needle, " says Reaumur, "compared to 



the sting of the gnat, is the same as the 



point of a sword compared to that of the 



needle." How is it then that so small 



a wound does not heal at once ? How 



is it that small bumps arise on the part 



that is stung ? The fact is, that it is not 



only a wound, but it has been imbued with 



an irritating liquid. Fips 25 ' 26 27 



This liquid may be seen to exude, under 



different circumstances, from the trunk of the gnat, like a drop of 

 very clear water. 



Reaumur sometimes saw this liquid even in the trunk itself. 

 " There is nothing better," he observes, " to prevent the bad 

 effects of gnat bites than at once to dilute the liquid they 

 have left in the wound with water. However small this wound 

 may be, it will not be difficult for water to be introduced. By 

 rubbing, it will be at once enlarged, and there is nothing to do 

 but to wash it. I have sometimes found this remedy answer 

 very well." 



The gnat is not always in the form of a winged insect, greedy 

 for our blood. There is a period during which they leave us in 

 repose. This is the larva period. It is in water, and in stagnant 

 water in particular, that the larva of the insect which occupies 

 our attention is to be found. It resembles a worm, and may be 

 found in ponds from the month of May until the commencement 

 of winter. 



If we desire to follow the larva of the gnat from the 

 beginning, we have only to keep a bucket of water in the open 

 air. After a few days this water will be observed to be full 



