PRESERVING AND STUDYING INSECTS 



353 



having either end extend up above the top of the bottles. This 

 allows the trays to be stacked one above another without injuring 

 the bottles. 



Numerous substitutes for alcohol have been employed, of which 

 a 4 per cent solution of formaldehyde is probably the best, as it 

 is cheaper, tends to preserve the color, and does not harden the 



FIG. 489. The Marx tray for specimens in liquid 



specimens. This, however, is not much superior to alcohol, and 

 in many cases shrinks the specimens more than alcohol would. 



Material intended for dissection may be treated as above, but 

 if alcohol is used, should be permanently preserved in 70 to 85 

 per cent alcohol, to which 10 per cent of glycerin has been added. 



Inflating insect larvae. The larvae of most of the Diptera, 

 Coleoptera, and Hymenoptera are preserved in alcohol, as noted 

 above. It has been found, however, 

 that lepidopterous larvae may be 

 preserved much better by inflating 

 them, the method of which is as 

 follows : 



The larvae are brought to the 

 laboratory alive, and when ready to 

 be inflated are killed or stupefied in 

 a cyanide bottle. This method will 

 be found much better than killing 

 the larvae in the field, as they should 

 be blown as soon as possible after 

 they are killed. Remove the larva from the cyanide bottle and 

 place it on a piece of blotting paper. A glass tube or pencil is 

 next rolled over the body from the head toward the tip of the 

 abdomen. This causes the alimentary tract to protrude, which is 

 then snipped off at the anus by a pair of sharp-pointed scissors. 



FIG. 490. Homemade apparatus 

 for inflating larvae 



(After Washburn) 



