COLLECTING AND PRESERVING TNSECTS — BANKS. 



91 



carefully watching the collector may obtain some of the parasitic 

 species. Ants (fig. 159) can be secured anywhere, but it is better 

 to get at the nests and so secure the different forms at one time. All 

 the specimens from one nest should bear a number, as "Nest 16." 

 They may be collected in alcohol and mounted up as desired. The 

 social wasps and bumblebees may be gathered from the nests by 

 visiting them at nightfall and introducing chloroform, or carbon 

 bisulphide for those in the ground. One may thus gather all the dif- 

 ferent forms, which are not as yet known for many of our species of 

 these insects. 



The Micro-Ilymenoptera are sometimes collected in alcohol, espe- 

 cially those obtained in sifting. These can be prepared for mounting, 

 Mr. Crawford says, by removing them from the alcohol and placing 



Fig. 140.— A fossorial wasp, Ammopiiila nigricans. 



them in chloroform for a few minutes, and then out on blotting paper. 

 In many cases the genitalia of Hymenoptera are of value in deter- 

 mining the species. If the specimen is gently squeezed near the 

 tip of the body the genitalia will sometimes be extruded. Other- 

 wise they will have to be removed with a pair of fine scissors and 

 scalpel and mounted on a slide or on a bit of cardboard attached to 

 the pin. The nests and galls of Hymenoptera should be collected 

 whenever possible. The galls may be pinned in the boxes, but a 

 better way is to put them in flat pasteboard boxes of a size suitable 

 to be arranged in rows in the box or drawer, with a label on the upper 

 edge of each box indicating the contents. Casts of holes may be 

 obtained by pouring into them mixtures of cement or plaster of 

 Paris. 



