370 Phylum Art hr op oda 



into which the adults will emerge, should have a relative humidity of 

 from 85% to 100%. Marked or rapid changes in temperature, aside from 

 any deleterious effect upon the craneflies and their food material, cause 

 much difficulty and frequent losses from their effect upon moisture con- 

 ditions. Condensed moisture on the sides of the jar traps and kills the 

 adults, and, falling on the larval medium, damages its surface and may 

 drown larvae or pupae. This is particularly true when the medium is 

 silt or agar. Exposure of the rearing jar to direct sunlight is especially 

 to be avoided. 



Except for larvae from markedly acid or basic habitats (sphagnum 

 bogs and swamps or seepage from limestone cliffs) considerable varia- 

 tions in pH are tolerated. Since it is necessary to keep the jars closed 

 to maintain a high humidity, it is advisable to have a comparatively large 

 air space in proportion to the space filled with the larval medium, and to 

 include a few small green plants (usually mosses, liverworts, or algae) for 

 photosynthesis. 



All predacious larvae are strongly cannibalistic in rearing jars, even if 

 well fed, and should be isolated. Stacked finger bowls or jelly glasses, 

 the centers of the tin lids of which have been replaced by fine meshed 

 wire gauze, make good culture dishes. The younger instars of many 

 species of Tipula are also somewhat cannibalistic when crowded and, since 

 the females lay from 200 to 300 eggs, are very likely to be crowded if the 

 full complement is oviposited in one jar. However the survivors appear 

 to thrive upon such a diet and, if the culture is well supplied with food, 

 the number of larvae is only reduced to the proper population for the 

 space provided. 



For a number of species in groups I, II, III, and IV, it has been pos- 

 sible to maintain a continuous culture of successive and overlapping 

 generations in one large rearing jar with no more attention than to 

 maintain proper conditions of moisture and food. For a maximum pro- 

 duction of individuals, however, it is better to start one or more new 

 cultures from each mated female. 



If sufficient space above the larval medium is provided in the rearing 

 jar (500 cc. or more for large species, 4,000 cc. for the larger Tipula), 

 the adults of the majority of species will mate and oviposit. It is usually 

 preferable, however, to remove the newly emerged adults to a large glass 

 jar, kept humid by a carpet of wet filter paper, where mating and often 

 oviposition will take place. If one can obtain recently emerged males 

 and females at the same time there is no necessity to provide food, since 

 mating and oviposition are usually completed within 48 to 72 hours and 

 water is obtained from the wet filter paper. If adults are emerging 

 slowly so that individuals of both sexes are not always available, the 

 adults may be kept alive for one or two weeks by providing food and 



