FOLSOM: MOUTH-PARTS OF OKCHESELLA CINCTA. 33 



Orchesella cincta is a common species among decomposing leaves and 

 in moss ; it is most abundant among decaying pine needles and twigs, 

 upon which it feeds. The stomach usually contains minute irregular 

 fragments of wood, and the insect thrives when confined in a glass tube 

 with a moistened piece of decaying pine wood. 



The observing Dr. Fitch ('63) is the only naturalist who has given 

 any account of the feeding habits of Collembola. I quote his observa- 

 tions ('63, p. 672) upon Smynthurus hortensis : "These Garden Fleas 

 are so minute that the human eye without the aid of glasses is wholly 

 unable to inspect their movements. The following observations will 

 therefore be the more interesting to the reader. It is some years since 

 that I noticed several of these insects on a piece of new pine board lying 

 in the garden. Wondering what they could find to attract them to 

 that situation, where I thought the odor of any turpentine in the wood 

 w r ould rather make it repulsive to them, I was able to observe their 

 operations by approaching a magnifying glass to them gently, so as not 

 to alarm them and cause them to skip away, — ^he light colored surface 

 of the new wood enabling me to inspect their movements much more 

 accurately than could be done were they standing upon a darker colored 

 ground. Several of them were noticed, here and there, to have grasped 

 in their mouths what appeared to be an exceedingly minute flexible fibre 

 of the wood, fine as a fragment of a spider's web : and they were pulling 

 backward, at the same time shaking their heads slightly, evidently to 

 tear off these fibres. One of the fore legs was frequently used to crowd 

 this fibre more and more into the mouth, whenever it became peeled up 

 and too long to pull upon to advantage. Everything indicated that it 

 was for the purpose of food that they were thus tearing off this fine fuzz 

 from the surface of the new board. At one place was a small black spot 

 in the board, caused apparently by some old disease in the wood at this 

 point, which rendered it more soft and palatable to the insects, for two 

 of them were here busily occupied in gnawing the particles of matter 

 from the surface, as it seemed." 



The stout setoe which project from the labrum, palpi, and labium, and 

 surround the mouth, are probably tactile in nature. It is possible that 

 the food is moistened with saliva before being taken into the mouth, as 

 the median trough of the labium is well adapted to convey saliva to the 

 border of the mouth. 



In order to seize food, the mandibles leave their sockets and are pro- 

 truded a little from the mouth. The tips of the mandibles, by lateral 

 movements, grasp fibres of decaying wood, which are held between the 



