﻿SOLOMON ISLANDS TRIPTEROIDES — BELKIN 207 



pupae do occur in pure cultures, but associations based on the suppo- 

 sition that there is only one species in a given collection are dan- 

 gerous, since we know that morphologically similar species (sibling 

 species) may occur in the same habitat. Progeny rearings are even 

 more laborious than individual rearings and are not entirely satis- 

 factory, as the immature stages are subjected to artificial conditions 

 for a long period of time. The specimens obtained from such rear- 

 ings frequently lose many of the hairs and are generally weaker than 

 those obtained from individual rearings of wild larvae. On the 

 other hand, this method offers the opportunity to study individual 

 variation within a single "family." Ideally both methods should be 

 used in studying variation in populations of mosquitoes. This was 

 done with only a few species on Guadalcanal because of the difficulty 

 of obtaining gravid females in the field or inducing them to take a 

 blood meal. All specimens reared in the laboratory except pre- 

 daceous forms were reared on a combination diet of powdered 

 C-ration biscuit, yeast, and dried blood proteins. 



PREPARATION OF MATERIAL 



Sufficient time was not available to mount the majority of the 

 larval and pupal skins immediately following the rearings. The 

 most satisfactory method of preservation was found to be storage of 

 the skins in 50-percent ethyl alcohol. Specimens remaining in this 

 preservative for two and a half years made satisfactory mounts. 

 But it must be stressed that to obtain good skins it is necessary to 

 pick them out of the breeding containers within a few hours after 

 ecdysis. 



The cast skins or pelts, as they are sometimes called, were mounted 

 in euparal after passage through 95-percent alcohol and eugenol 

 (clove oil). Just as satisfactory were specimens dehydrated in cel- 

 losolve and mounted directly in euparal. Euparal was used in pref- 

 erence to balsam because it is easier to handle and dries much more 

 rapidly. To obtain good mounts it is necessary to use enough mount- 

 ing medium to allow the skins to retain their natural shape and not 

 be flattened. Flattened specimens are difficult to interpret because of 

 the distortion and crowding of hairs. In mounting larval skins of 

 Tripteroides it is necessary to stretch them by inserting a needle at 

 the base of the siphon and pulling this part away from the terminal 

 segments in which it is usually telescoped. Pupal skins must be dis- 

 sected to obtain a good view of all hairs. The abdomen, together 

 with the metanotum, is easily separated from the cephalothorax with 

 a needle passed from side to side. The cephalothorax is opened dor- 

 sally and mounted flat in one piece with the ventral surface in the 

 center and dorsal halves laterally. The abdomen with the metano- 

 tum attached is mounted with the dorsal surface uppermost. 



