[41] COLLECTING AND PRESERVING INSECTS RILEY, 



The Tenthredinidse (Saw-flies) are not so often found about flowers- 

 but usually remain in the vicinity of the food- plant of the larva^ 

 and may many of them be collected by sweeping. The larvsB of this^ 

 family are in many cases difficult to breed, as most of them are singie- 

 brooded, and it becomes necessary to carry the larvse over the winter. 



The Gall-liies, Cynipidse, are the easiest of the families to collect, 

 because of their abundance and because of the ease with which they 

 may be reared. Their galls occur in enormous variety on oaks of vari- 

 ous species and also upon brambles and certain common weeds. Thes& 

 should be collected when mature and be kept in glass jars. The Gall 

 flies and inquilinous and parasitic species may thus be easily obtained, 

 the former appearing at particular seasons and the latter emerging 

 from the galls at all seasons of the year, and sometimes continuing to 

 escape for a period exceeding two years. 



One of the most interesting families in this order is the Formicidse,. 

 which comprises the true ants. In the case of these insects isolated 

 specimens should not ordinarily be collected, and it is especially desir- 

 able to collect the species from col- 

 onies so that the three forms (males, 

 females, and workers) may be ob- 

 tained together. This holds also in 

 the case of the social wasps and bees, 

 but the different sexes of the latter 

 may be collected in a season's collect- 

 ing about flowers, the females and 

 workers in early spring and the males 

 in the fall. 



The Uroceridee or woodborers are to 

 be found only about trees in which the 

 larvae breed. They may frequently be 

 taken about tree trunks, or burrow- ^ „-, , -r ■. ,^ ^- . 



' Fig. 61. — An Ichnenmon {Ophion). 



ing with their long gimlet-like ovi- 

 positors into the trunks of trees to oviposit. Breeding is also a satis- 

 factory method of obtainiDg these insects. 



Some special methods of collecting Hymenoptera may be briefly out- 

 lined. In the case of the social bees, particularly bumble-bees, and 

 also the smaller wasps and yellow-jackets, a very satisfactory method 

 of collecting consists in first stupefying the insects in the nest by 

 introducing a small amount of chloroform, benzine, or bisulphide of 

 carbon. This should preferably be done in the late evening, after all 

 the insects have come in for the night. The nest may then be opened 

 and examined without any danger of being stung, and the different 

 forms may thus easily be obtained, together with any rare parasitic or 

 inquilinous insects. In the case of the nests of Bombi this is the best 

 method of obtaining the inquilinous Apathus species. 



On account of the danger of being stung, and also on account of 



