COLLECTING AND PRESERVING INSECTS BANKS. 73 



well preserved in alcohol as when dry, and, whenever one has an 

 abundance of specimens, it is well to put up some in tubes or vials 

 of alcohol. Specimens so preserved are better suited for dissection 

 or morphological studies than diy insects. 



The best kind of vial in which to keep alcoholic material is a flat 

 bottom necked vial like the ordinary homeopathic or "homo" vials 

 sold by all druggists. The kind kept in stock by drug stores is fre- 

 quently of poor quality, but they can order a better quality of 

 heavier glass if asked, or these can be purchased from dealers in 

 entomological and microscope supplies. It is best to have vials of 

 but two or three sizes, 1, 2, and 4 dram, and for a collection of one 

 group of insects one size will usually be sufficient. Many prefer to 

 use straight tubes instead of necked vials. These can be obtained 

 from the dealers. Professor Comstock has devised a square bent 

 necked bottle which enables one to put the specimen in the box with 

 the pinned insects; but it is better to keep alcoholic material in a 

 separate collection. Professor Riley also devised a method for 

 keeping vials in the collections, the bottle resting upon a block. 

 This method has been shown to be far inferior to keeping specimens in 

 the ordinary upright bottles. Others put a pin through the stopper 

 of the vial and pin the bottle at a slight angle in the collection. But, 

 as before stated, it is far better to keep alcoholic material by itself 

 than mixed with the pinned specimens. 



Cork stoppers, if of good quality, are superior to any other kind, 

 but the difficulty is in obtaining good cork. The extra expense of 

 the best quality of cork will be repaid by the better results. As 

 one goes over his collection from time to time those stoppers that are 

 poor can be replaced by new ones. The trouble in getting good 

 cork stoppers has led many to the use of rubber. The great majority 

 of rubber stoppers that are placed on the market are of poor quality 

 and form crystals of sulphur which fall upon the specimens. This 

 tendency may be reduced, it is claimed, by soaking the stoppers 

 for an hour or so in hot water. To insert a rubber stopper in a vial 

 one should put beside it a slender insect pin. This enables the 

 compressed air to escape; when the stopper is fully in, the pin is 

 withdrawn. 



The percentage of alcohol to be used varies with the group of 

 insects. If the insects have a hard body, 90 to 95 per cent will not 

 injure them, but for most soft-bodied forms, as larva? and spiders, 

 70 to 80 per cent is better. A good plan is to put the specimens first 

 in a weak solution, 60 to 70 per cent, and then Later in a stronger 

 liquid. For many larvae it is well to dip. them into boiling water, or 

 just bring them to a boil in water, before placing them in alcohol. 

 One of the disadvantages of alcohol is its rapid evaporation. If the 



