THE WOOD-BORERS 



After the storing process is completed the female 

 seals up the nest with mud. In the case of one rubro- 

 cinctum that we were watching, she began to close the 

 opening at four in the afternoon and finished her work 

 just thirty minutes later. In this time she made ten 

 journeys for mud, bringing it in pellets in her mandibles. 

 In another case, also a rubrocinctum, the female, after 

 bringing so many spiders that the cell was full up to the 

 very door (which we saw in no other case), went away 

 without closing it, and never returned. The male seemed 

 uneasy at her conduct, and several times flew away, 

 staying an hour or two and then returning ; but after a 

 time he too deserted the nest. Whether some evil fate 

 overtook the female or whether there was some failure 

 of instinct on her part, can only be conjectured; but the 

 latter hypothesis is not untenable, since out of seventy- 

 six nests that we had under observation seven were 

 cleaned out and prepared and were then sealed up 

 empty. We have often found similar cases among the 

 nests of the blue mud-dauber wasps, where it is not a 

 very uncommon thing for the absent-minded females to 

 build their pretty little cylindrical nests with infinite 

 care and patience, and then to seal them up without put- 

 ting anything inside. 



Cocoons of rubrocinctum that were gathered in the 



189 



