256 ENTOMOLOGICAL NEWS. [June, '(X) 



tion for study. I do not present this paper as an original con- 

 tribution to scientific literature, but I hope that it may be help- 

 ful to entomologists who have not given special attention to 

 this group. 



I believe that the most satisfactory way to preserve aphids 

 for general purposes is to keep them permanently in 70 per 

 cent, alcohol. It is advisable, however, to put the more deli- 

 cate species in 35 per cent, for several hours before trans- 

 ferring them to 70 per cent. In this strength there is very 

 little, if any, shrinkage. All species remain comparatively 

 soft and the appendages more flexible and less liable to break 

 than in 95 per cent, alcohol. Good mounts can be made with 

 them at any convenient time. Alcoholic specimens should 

 be kept in three or four times their bulk of fluid. If too many 

 aphids are put in a vial, the alcohol will become weaker than 

 70 per cent, and may not be strong enough to preserve them 

 permanently. If it is necessary to keep a large number of 

 insects in one vial, the fluid should be changed once or twice 

 a few hours after they are put in. Mr. Theo. Pergande, of 

 the U. S. Department of Agriculture, Bureau of Entomology, 

 advised this percentage in a letter to me, dated October 23, 

 1906. 



Aphids preserved in about 2^/2 per cent, formalin can be 

 absolutely depended on not to shrink. If they are fixed in 

 hot water at about 80 degrees C. and are pricked when suf- 

 ficiently hard and are kept in the dark, they will partly retain 

 their normal color and have the advantage of looking much 

 like the real living insects. They cannot be pricked while 

 fresh without losing some of their contents and thus affect- 

 ing their shape. Fine sewing needles (Sharps No. 12) are 

 suitable tools for pricking small aphids. All forms can be 

 readily submerged, if they are first passed through 05 per 

 cent, alcohol to remove waxy secretions and to dampen the 

 entire external surface and thus prevent the formation of a 

 film of air around them when the formalin is poured on. 

 They must not be left more than a very few minutes in the 

 alcohol. These specimens will always be good material for 



