398 TROPICAL WILD LIFK IN BRITISH GUIANA 



telling black. Then comes the final gift of nature, the power 

 of motion. The nascent creature moist with birth, bursts its 

 cocoon, gnaws through the plug of mortar and issues into the 

 outer world, a perfect insect. Only thii'ty-eight days have 

 passed since I placed the tubes in the laboratory, and since 

 the parents of this new creatiu-e arrived, realizing their 

 destiny. 



There is an interesting problem to solve concerning the 

 black reed-wasps. Their nests vary considerably in number 

 of cells. Some are complete with one, others contain two, 

 but the majority are complete only after an egg has been 

 laid upon the stores in three separate compartments. The 

 question arises, how will the wasps emerge as perfect insects 

 without disturbing one another? 



If the nest is to shelter three insects, the cell farthest 

 from the entrance will natiu'ally receive the first provisions 

 collected, and it would seem, in due time, the first egg de- 

 posited. The remaining two cells would receive their re- 

 spective contents in the order of their position, but the first 

 egg laid, naturally hatches before the others. The grub, 

 reaches maturit}, pupates and is ready to emerge sometime 

 ahead of its sisters in the other cells. What happens then? 

 Does the issuing wasp burrow its way out through the cells 

 in front, upsetting in its passage the vital condition of soli- 

 tude that surround the younger insects? Does it burrow 

 through the clay plugs, separating each nursery and as a 

 final act of vandalism, leave the nest open, exposing its 

 younger sisters to the first parasite? 



So it would seem, })ut such a course would be contrary 

 to all the laws of nature. She does not destroy her children 

 needlessly, yet I wonder what happens in such nests as that 

 of the bhick reed-wasp, whose oldest cliild seems farthest 

 from the door to freedom! 



Perhaps the parent wasp is gifted with the power of 

 laying eggs that require varied terms of incubation. In the 

 first cell ])r()visioned she lays an egg that requires three days 



