COLLECnON OF AQUATIC INSECT LARVAE 73 



For identification of the aquatic larvae it is of course 

 necessary to breed them through to the adult stage. In 

 the Odonata and P]phemerida this does not mean the loss 

 of the larva for description, as there is no pupation and 

 the enjpty exuviated skin preserves the form of the larva 

 almost perfectly. The colours are lost, but as the larvae 

 are long-lived, there is plenty of chance to describe the 

 living animal. 



The more easily secured aquatic insect larvae are found 

 in muddy and sandy parts of spruits. A most convenient 

 outfit for collecting them is a garden rake and several 

 small jars of water. Wherever the water is not swift, 

 the mud from the edges and the bottom down to tv/enty 

 inches deep can be raked ashore. The animals in it emerge 

 from it and crawl to the water again : they are all slow 

 enough so that nearly every one may be picked up. I 

 ])refer my fingers to any scoop or forceps for seizing 

 them. In such places will be found larvae of Odonata, 

 Ephemerida, and the worm-like larvae of several small 

 midges (Diptera). 



By holding a scoop-net in the stream just below a 

 rocky rapid place, and having someone overturn the 

 rocks lying loose in the stream's bed just above the net, 

 a number of larvae of Tipulidae, etc., will be dislodged 

 and will be swept into the net. 



Mosquito-pools are worth prospecting, both in the water 

 and in the mud forming their bottoms. 



The breeding of the swift-water forms requii'es an 

 aquarium which has a continuous supply of running 

 water. Mosquito-netting spread over the top of the 

 vessel will of course prevent the adults from disappear 

 ing when they emerge. 



The forms inhabiting relatively motionless water may 

 "be kept alive in trays indoors, in which the water is 

 renewed occasionally. They must, liowever, be fed To 

 f^ecure more natural conditions and permit of growth and 

 metamorphosis under study, Needham has devised a 

 simple aquatic cage. This is simply the frame of a box, 



