566 PHYSIOLOGY. 



mals which can least bear the withdrawal of air, as some instances cited 

 above prove their great tenacity of life, they are yet doubtlessly the 

 animals in which respiration of atmospheric air is most perfectly deve- 

 loped, and may therefore especially lay claim to the distinction of air 

 animals. If now, proceeding from another point of view, we should 

 characterise those groups among insects which of all chiefly reside in 

 the air, they are doubtlessly the Lepidoptera, to which succeed in the 

 order of their respective claims the Hymenoptera, Diptera, and Libcl- 

 lulee (compare 125, 126). 



There is not a single species among the Lepidoptera which dwells in 

 the water or exclusively upon the ground, all seek the air, and flutter 

 about in it, with the exception of a before-named apterous female. 

 Even their larvae, more than the larvae of any of the other orders, seek 

 a place in the air, and are best contented in this element. There is but 

 one caterpillar of a moth (Botys stratiotalis) as yet observed to be an 

 inhabitant of the water, Avhereas the caterpillars of some of the Nuctuce 

 (Nociua graminis, &c.) are found among stones, or at the roots of 

 grass, others in the stems of plants (Noctna typhce, &c.), or in fruits 

 {Tinea (Carpocapsa) pomona, c.) Similar habitats in concealed 

 places less accessible to the air are peculiar to several of the inferior 

 families of the Lepidoptera, whereas the more perfect ones, for instance, 

 the butterflies and crepuscular moths, all live in the open air upon 

 plants. The perfect insects of each family, lastly, are constantly in 

 motion during that portion of the day in which the time of their growth 

 as larvae falls, and then only occasionally repose : thus the butterflies 

 are found on wing in the sunshine during day, the crepuscular moths 

 and Noctuce in the twilight ; the Tinea, again, chiefly by day, but 

 especially towards the afternoon. 



The Hymenoptera are, the next to these, the principal air insects ; 

 they also, in their perfect state, are never found in the water, and as 

 rarely as larvae; yet at this early stage of their existence they consi- 

 derably diverge from aerial life, and live chiefly in confined close places, 

 for instance, in holes in the ground, in nests, in the excrescences 

 of plants, in their stems, and parasitic within other larvae. The 

 pseudo-caterpillars of the saw-flies only seek the air, and dwell in it 

 openly upon leaves. The perfect insects possess excessive motion, are 

 constantly flying about in the. air and sucking flowers, and the females 

 only of some of them as well as the neuter ants are deprived of the 

 power of flying. 



