24 THE INSECT WORLD. 



From this it follows that if the horse possessed the same strength 

 as this last insect, or if the insect were the size of a horse, they 

 would either of them be able to draw 56,700 lbs. M. Plateau has 

 ascertained the pushing power in insects, by introducing them into a 

 pasteboard tube, the interior of which was made rough, and in which 

 was fixed a glass plate, which allowed the light to penetrate into the 

 prison. The animal, if excited, struggled with all its strength against 

 the transparent plate, which, on being pushed forward, turned a lever 

 adapted to a miniature dynamometer, which indicated the amount of 

 effort exercised. 



The results thus obtained prove that the pushing power, like the 

 power of traction, is greater in inverse proportion to the size and 

 weight of the animal. A few figures will better explain this curious 

 law. In Orydes naskornis the proportion of the pushing power to 

 the weight of the insect is only three to two ; in Geotrupcs sferco- 

 rarius it is sixteen to two ; and in Onthophagus niickicornis seventy- 

 nine to six. 



Experiments have been made on the lifting power of insects by 

 fastening a ball of soft wax to a thread attached to the hind legs. 

 The proportion of the weight lifted has been found equal to that of 

 the body. That is to say, the insect when flying can lift its own 

 weight. This is proved by the following calculations : — In the 

 Neuroptera the proportion is i in the Dragon-fly {Libellu/a vulgata)^ 

 •7 in Lestes sponsa. In the order Hymenoptera it is 78 in the bee, 

 and •63 in Bombus terrestris, the humble-bee. In the Diptera it is 

 •9 in CaUiphora vomitoria* 1-84 in the Syrphus corollce^ and 177 in 

 the house-fly. 



These results show that insects have only sufficient power to 

 sustain their own weight when flying, as the above calculations 

 exhibit the maximum of which they are capable, and at the utmost 

 this strength would only compensate for the fatigue occasioned by the 

 action of flight. 



At the same time it is to be observed that the Diptera, and 

 among others the house-fly, can sustain their flight longer than the 

 Hymenoptera and Neuroptera, although one would not think so 

 from their appearance. In conclusion, if an insect's power of flying 

 is not considerable, its power of traction and propulsion are immense, 

 compared with the vertebrate animals ; and, in the same group of 

 insects, those that are the smallest and lightest are the strongest. 

 The proportion between the muscular strength of insects and the 



* The meat-fly. — Ed. 



