iv. 6. 109 



external, it were of stouter build, as in scorpions, its weight 

 would interfere with flight. As for scorpions, they never rise 

 from the ground, and their piercer or sting must therefore 

 be arranged in the way it is, as otherwise it would be of no 

 use as a weapon.^^ The Diptera never have a tail-sting. ^^ For 

 the very reason of their being dipterous is that they are small 

 and weak, and therefore require no rnore than two feathers to 

 support their light weight. And the same reason which reduces 

 their feathers to two causes their piercer or sting to be in 

 front ; for their strength is not sufficient to allow them to strike 

 efficiently with the hinder part ^* of their body. Polypterous 

 insects on the other hand are of greater bulk — indeed it is this 

 which causes them to have so many feathers — and their greater 

 size makes them much stronger in their hinder parts. These 

 insects therefore have tail-stings. For it is better, when possible, 

 that one and the same instrument shall not be made to serve 

 several dissimilar uses ; but that there shall be one organ to 

 serve as a weapon, which can then be very sharp, and a second 

 distinct one to serve as a tongue, which can then be of spongy 

 texture and fit to absorb nutriment. Whenever, therefore, nature 

 is able to provide two separate instruments for two separate 

 uses, without the one hampering "the other, she does so, instead 

 of acting like a coppersmith, who for cheapness makes a spit 

 and lampholder in one. It is only when this is impossible, that 

 she uses one organ for several functions.^^ 



The anterior legs are in some cases longer'^ than the others, 

 that they may serve to clean off the dust or other matter which 

 may fall into the insect's eyes and obstruct its sight, which already 

 is not very distinct owing to the eyes being made of a hard 

 substance. Flies and bees and the like may be constantly seen 

 thus dressing themselves with crossed fore-legs. Of the other 

 legs, the hinder are bigger than the middle pair, both to aid in 

 running and also that the insect, when it takes flight, may spring 

 more easily from the ground. This difference is still more marked 

 in such insects as leap, in grasshoppers for instance and in the 

 various kinds of fleas.^^ For these first bend and then extend 

 the legs, and, by so doing, are necessarily sl^ot up from the 

 ground. It is only the hind legs of grasshoppers, and never 

 the front ones, that resemble the two long stern oars by which 

 a ship is steered.^^ For it is essential that the joint shall be 

 683 b. 



