1022.] 157 



artificial light in houses, I have only once seen it on the wing out 

 o£ doors. 



In the Sudan, Blattella siipellectilium apparently breeds throughout 

 the year, and every stage of development may be seen at all seasons. 

 A male fertilizes several females. A female produces many broods, each 

 of which is not necessarily dependent on a fresh mating. The jn'olific 

 increase of this cockroach is checked by a hymenopterous parasite which 

 develops in the egg-capsule. 



In order to trace the life-history of this insect, a number of experi- 

 ments were carried out in 1915. Cockroaches are not difficult to keep 

 alive in confinement, if kept clean and fed and watered regularly. Those 

 used in the following experiments were kept in large glass basins covered 

 wdth glass lids, and were fed on table scraps. The food was supplied daily 

 and the remains of the previous day's supply carefully removed. If the 

 old food was not removed it became mouldy and the insects died. 



A young fi-eshly matured male was caught and used to fertilize the 

 females until a male had been bred out. Afterwards specimens which 

 had been bred \\ere used. 



Index of the specimens used in Experiment 1. 



No. 1. Female matured on May 2nd Died June 13th, 



2. Female matured on May 2nd Died July 18tli. 



3. Male caught May 4th. 



4. Male matured on May 15th Died July 16th. 



The females, Nos. 1 and 2, were kept with a male, No. 3, from 

 May 4th until May 15th ; on that date he was released and male No. 4 

 added. 



Index of the specimens used 171 Experitnent 2. 



No. 5. Male matured on August 20th Died Oct. 19th. 



6. Female matured on August 29th Died Oct. 12tli. 



7. Female matured on August 30th Died Oct. 30th. 



These cockroaches were reared from one brood and kept together. 

 The male was eventually killed by accident. No eggs were developed 

 after the male was absent, although No. 7 female lived approximately 

 21 days later. 



From these experiments it was found that these cockroaches laid 

 their eggs in an average period of 13'75 days after attaining maturity', 

 the maximum being 17 and the minimum 10 days. The average period 



