10 



Some Solitary Wasps of Texas. 



August 11, 6 p. m. Larva nearly finished spinning cocoon. 



August 29. Adult emerges. 



Thus the length of the egg stage of 0. arvensis is about two and 

 a half days; of the larval stage, four and a half days; of the pupal 

 stage, eighteen days. 



Another nest which I observed an arvensis store and close on 

 August 14th I opened nearly a month later (September 9th), I 

 was expecting to see a wasp emerge by this time, and had placed 

 a bottle over the entrance to receive it. I found in the nest no 

 offspring of the wasp, but the red pupa of a fly and fourteen cater- 

 pillars, of which four had dried up, three were dead though in 

 good condition and seven actually alive. The caterpillars' length 

 of life is so striking that I deem it desirable to add the following 

 table : 



CONDITION OF CATERPILLARS. 



Date. 



September 9... 

 September 14. 

 September 19. 

 September 26., 

 September 29. 

 October 11 



Besrun to shrink. 



Dead but plump. 



Alive. 



Thus three caterpillars lived 43 days, one 46 days and one re- 

 mained, for 58 days, in a condition good enough to be added to any 

 waspling's bill of fare. 



A survey of these few facts would seem to indicate that, while 

 the suspension of the egg and the young larva is a desirable con- 

 dition and increases their chances of successful development, yet 

 it is not an essential condition, as Fabre has contended. Nor is 

 it essential, in consideration of the longevity of the paralyzed prey, 

 that the caterpillars be devoured in the order in which they were 

 stored. 



