June, '09] ENTOMOLOGICAL NEWS. 255 



Aphid technique.* 

 BY PAUL HAYHURST. 



Plant lice and similar soft-bodied insects are often con- 

 sidered difficult objects to preserve permanently in good con- 

 dition. They cannot, of course, be pinned, for their dried 

 bodies give little or no idea of what the real insect is. On 

 the other hand, strong alcohol is apt to cause considerable 

 shrinkage and the appendages become more or less brittle 

 and easily broken. Large specimens are not so much in- 

 jured as the smaller forms, which usually shrink badly. The 

 more delicate species frequently lose much of their pigment, 

 especially in the abdominal regions. Shrunken or distorted 

 material is valueless for accurate measurements and is often 

 so unsatisfactory in other respects that specific determination 

 becomes a matter of conjecture. Alcohol is therefore rarely 

 used by some investigators w'ho mount most of their speci- 

 mens for permanent preservation. It is, however, an evident 

 advantage to be able to put up plenty of material quickly and 

 easily, but if all the insects must be mounted as they are col- 

 lected, comparatively few can be kept of each species. This 

 is inadvisable, since to describe a form properly many speci- 

 mens must be examined to note the variations in size, struc- 

 tural characters and markings, for then it is probable that 

 fewer species would be manufactured. 



An ample supply of specimens is also a real privilege in 

 making mounts, and it allows exchanges with other workers. 

 Mounting aphids in balsam is, furthermore, a great nuisance 

 on a collecting trip. If a field agent must carry such slides 

 with him as he goes from town to town, some of them at 

 least are liable to be ruined in transit before the balsam sets, 

 unless it is first hardened by heat. My own material pre- 

 served in the usual way has been so unsatisfactory that I 

 have recently given considerable attention to the technique 

 and consequently I now find my specimens in suitable condi- 



*Contributions from the Entomological Laboratory of the Bussey 

 Institute, Harvard University. No. 3. 



