308 Phylum Arthropoda 



giving the desired relative humidity and tightly corked. The vials were 

 also aerated once a day. 



To determine the length of life of the ist instar nymphs without 

 food the nymphs were placed in No. ooo gelatin capsules in which many 

 holes had previously been punched to allow a free circulation of air. 

 The capsules were put in a small screen cage which was suspended in 

 a pint Mason fruit jar containing a saturated solution of the salt giving 

 the desired relative humidity. Aeration of the jars was performed daily 

 as in the previous experiments. 



Bibliography 

 Jones, R. M. 1930. Ann. Ent. Soc. Amer. 23:105. 



Family hydrometridae 



HYDROMETRA* 



"Hydrometras are easily kept in captivity and breed in aquaria, thriv- 

 ing on a diet of flies and other small, soft-bodied insects. They are, 

 therefore, ideal for observation." 



Family 



GERRIDAE 



THREE SPECIES OF GERRIDAE** 



GERRIDS are not easy to rear for the reason that they do not lend 

 themselves readily to life in captivity. If good-sized containers are 

 used and placed well back on the laboratory table, the specimens are 

 less likely to injure themselves by dashing against the sides. If placed 

 near the edge of the rearing table the striders will be disturbed each time 

 someone passes. At feeding and observation time the bugs make frantic 

 efforts to escape and in so doing continually butt against the sides of the 

 breeding jar. Observations may not be made if the rearings are carried 

 on in a large container, unless one has access to a movable-arm binocular. 

 A recently captured female Trcpobates pictus laid a small mass of eggs 

 on the underside of a small willow twig that was placed in the aquarium 

 jar. Individuals reared in captivity and depositing eggs every day will 

 usually fail to deposit eggs the first day after they are placed in a new 

 breeding jar. 



* From an article in Ent. Amer. 7:87, 1926, by J. R. De La Torre Bueno, Tucson, 

 Arizona. 



** Abstracted from an article in Ann. Ent. Soc. Amer. 17:419, 1924, by William E. 

 Hoffmann, Lingnan University. 



