132 WORK AT HOME AND IN THE FIELD 



either hold it near a fire or rest it in the drying oven till it is quite 

 dry and rigid. 



If you have done your work neatly, the skin and blowpipe will 

 both be quite air-tight when the clip is closed ; and the air, finding 

 no outlet, will still further inflate the skin when it expands on 

 exposure to heat. This is the reason why you are directed to blow 

 it out to something short of the natural dimensions. If you find 

 that this expansion causes the skin to stretch beyond its normal 

 size, a little of the air must be allowed to escape while it is yet soft 

 and flexible. 



The front of the larva is generally the last portion to become 

 dry, and when this is quite rigid the skin may be removed from 

 the blowpipe. This is a matter that requires the greatest care ; for 

 the skin is so very thin and brittle that a little rough handling will 

 break it to pieces. As a rule it may be easily pushed off the pipe 

 by a slight pressure behind, or a gentle twisting motion will loosen 

 its hold ; but this latter method can hardly be applied to hairy 

 larvae without breaking off the hairs, now rendered very brittle by 

 the heat. 



If you find the slightest difficulty in detaching the skin of a 

 valuable specimen, it is far better to damage the blowpipe than to 

 risk spoiling the skin. Supposing your blowpipe is a glass one, 

 you can easily break off the end of it after making a cut with a very 

 small triangular file, and the portion thus removed may be left 

 attached to the skin. Then, after softening the glass blowpipe in a 

 gas flame or the flame of a spirit lamp, it can be drawn out thin 

 again for future work. Those who can manipulate glass tubing in 

 this way will find it far better to lay in a stock of suitable material, 

 drawing it out when required, than to purchase blowpipes ready 

 made at the naturalist's shop. 



Very fine hollow stems, such as those of the bamboo cane, may 

 be used instead of glass ; and these possess the advantage of being 

 easily cut with a sharp knife when there is any difficulty in remov- 

 ing the skin. Again, whether glass or fine stems are used, a little 

 grease of any kind placed previously on the end will allow the dried 

 skin to be slid off with less difficulty. 



Preserved larvae should preferably be mounted on small twigs 

 or artificial imitations of the leaves of the proper food plants. A 

 little coaguline applied to the claspers will fix them very firmly on 

 these twigs or leaves, which are then secured in the cabinet by 

 means of one or two small pins. 



