[117] COLLECTING AND PRESERVING INSECTS RILEY. 



moisture gathers inside the glasses the top should be removed for a 

 short time. Larva- may also be placed upon growing plants. These can 

 be planted in flowerpots and the young caterpillars kept from wander- 

 ing either by a cage of wire netting or, by what I have found very sat- 

 isfactory, glass la nip chimneys. These can be placed over the plant, with 

 the bottom pushed into the earth, and then should have a loose wad 

 of cotton batting in the top. This has the double effect of preventing 

 too great evaporation of moisture and keeping its occupants within 

 bounds. Some larvae wander very much and climb with the greatest 

 ease over glass, spinning a silken path for themselves as they go. 

 When caterpillars are bred in the study it must not be forgotten that 

 the air inside a house is much drier than it is out of doors amongst the 

 trees and low herbage, where caterpillars live naturally. The amateur 

 will require some experience in keeping the air at a right degree of 

 moisture when breeding upon growing plants. In close tin boxes or 

 jars, where the leaves must be changed every day, there is not so much 

 trouble. An important thing to remember with larva? in jars is to 

 thoroughly wash out the jars with cold water every day. If, however, 

 a caterpillar has spun a web on the side and is hung up to moult, it 

 must not be disturbed. In changing the food it is better not to remove 

 the caterpillars from the old food, but having placed a new supply in 

 the jar, cut off the piece of leaf upon which they are and drop it into 

 the jar. If they are not near the moult a little puff of breath will gen- 

 erally dislodge them. Some caterpillars, as Papilio turnus, which spins 

 a platform to which it retires after feeding, can best be fed upon a liv- 

 ing tree out of doors, but must be covered with a gauze bag to keep off 

 enemies. A piece of paper should be kept attached to each breeding 

 jar or cage, upon which regular notes must be taken at the time, giving 

 the dates of every noticeable feature, particularly the dates of the 

 moults and the changes which take place in the form and color at that 

 time." 



The necessity of outdoor work is further felt in the determination of 

 the facts in the life-history of some insects which have an alternation 

 of generations, as some Gall-flies f Cynipidae), and most Aphides. To 

 successfully study these insects constant outdoor observation is neces- 

 sary, or the species must be inclosed in screens of wire or netting out- 

 doors on their food-plant. Many insects which breed on the ground 

 or on low herbage may be very successfully watched and controlled by 

 covering the soil containing them or the plant on which they feed with 

 a wire screen or netting. The use of wire screens is also advisable in 

 the case of wintering pupse or larvre out of doors. Many species can 

 be more easily carried through the winter by placing them outdoors 

 under such screens during the winter, which insures their being sub- 

 jected to the natural conditions of climate, and then transferring them 

 to the breeding cage again early in the spring. This is advisable in 

 the case of Microlarva3 and pupa?. Species which bore in the stems 

 of plants may be easily cared for and leaf- mining and leaf-webbing forms 



