PRESKRVING INSECTS 



19 



Fig. 22 Inflated \nr\ 

 (original). 



a, showing method of mountiu^f 



More elaborate apparatus can be employed if desired. Some use pneu- 

 matic bulbs for forcing the air into the larval skin, but human lungs 

 permit a more delicate ad- 

 justment to need?. A lamp 

 chimney can be placed 

 nearly horizontally over a 

 source of heat and serve 

 as a drying oven, or one 

 may be constructed of tin. 

 The latter is by no means 

 necessary and a busy 

 worker will soon depend 

 only on a blowpipe and a convenient lamp It is well for the beginner 

 to secure a number of rather large common larvae and practise on them. 

 After a caterpillar is well inflated, it must be removed carefully from 

 the blowpipe and mounted. Though it is desirable to have larvae ar- 

 ranged on their food plants, many will prefer to mount them on pins. 

 Twist a light wire round a small cube of cork and bend as represented in 

 the accompanying figure. The two free ends are brought together and 

 gently inserted into the body cavity, their elasticity serving to hold the 

 inflated larva in place, and a pin is thrust through the cube of cork. 

 Some use a straw in place of the wire, pinning through the free end. In- 

 flating and mounting on pins permits the placing of the specimens in 

 cases beside the adults. 



Alcoholic material. Many larvae and other soft forms can not be 

 preserved by any of the preceding methods. They should be placed in 

 small vials in 50% alcohol for a day or two, this replaced by 65% and 

 that in turn by 75 to 85% alcohol. If attention is paid to changing the 

 preservative fluid many larvae will keep well. White forms, as for 

 example grubs and some caterpillars, change color less if they are dropped 

 for a moment in boiling water before being placed in the alcohol. 



Vials and their care. The vial should be no larger than necessary 

 to hold the specimens and may have various shapes. Ordinary straight 

 vials, preferably with no neck, should be stored in small racks in an 

 upright position or the alcohol will escape more or less by capillary 

 action. As it is desirable to have all the stages of an insect together, 

 various plans have been devised for keeping alcoholic material in cases 

 with the adults. For trays bent necked vials are much used. In the 

 United States national museum the ordinary round vials with bent necks 



