56 PHIL RAU AND NELLIE RAU 



Summary of the Kansas winter brood 



The 4,397 cocoons from our 643 nests fall into the following 



classes : 



No. Per cent 



Cells giving good adults 172 4 



Cells sealed and filled with spiders, but no egg 537 12 



Cells sealed entirely empty 176 4 



Cells unsealed with few spiders and no egg 7 



Cells unsealed and empty 119 3 



Cells having dead larva and insufficient food 46 1 



Cells having dead larvae and sufficient food 245 6 



Cells having dead prepupae 1044 24 



Cells having dead pupae 110 2 



Cells having dead adults 130 3 



Cells infested by Melittobia 1524 34 



Cells infested by Anthrenus 171 4 



Cells containing cuckoo bees, Diptera, Trypoxylon, etc. . . . 116 3 



4397 100 



Thus the elimination in this lot is so high that we are almost 

 forced to believe that this is in some way an abnormal popula- 

 tion. It is clear that the species could not endure under this 

 rate of elimination indefinitely — in fact, at this rate the species 

 would be exterminated in four years. We know that the abun- 

 dance of any species varies from year to year, according _ to 'its 

 environment. We may have taken this sample after the popu- 

 lation had just passed through especial adversity, such as a 

 severe winter, a raid of parasites, etc. 



There is a possibility also that a fault exists which we could 

 not avoid in the collection of the material, and that a few old 

 nests of a former year or brood were mixed with these. While 

 collecting them we were careful to keep only those nests which 

 had no openings of egress or other evidence of their being old; 

 hence it is clear that unbroken old nests wherein the young had 

 died in an early stage or had been riddled by parasites, would 

 be indistinguishable from those of the present brood. The 

 number of old nests cannot be large, however, because most 

 of the nests gave positive evidence of newness in at least a part 

 of their cells. 



THE ST. LOUIS WINTER BROOD OF 1913 



In the early spring of 1913, 31 nests containing 171 cells of 

 these two species of mud-daubers were taken at Meramec High- 

 lands, near St. Louis, Mo. 



