136 WASP STUDIES AFIELD 



here illustrate the interior (fig. 32) of an abandoned cell of 

 the mud-dauber partitioned and resealed and containing two 

 clavatum cocoons, we have also long suspected that they 

 adapt and use in the same manner the holes already made by 

 other insects in logs and fence-posts. Knowing from our 

 observations that she frequently makes her nest in old 

 borrowed cells, our surprise was great when we found that 

 T. clavatum can also deftly tunnel into wood and make her 

 own burrow. This shows a greater diversity in activity than 

 is often found in wasps. It is indeed wonderful that so 

 high a degree of specialization should be associated with 

 such diversity of accomplishments or habits as we find in 

 this wasp. 



FIG. 32. The abandoned cell of a mud-daubing wasp remodelled to 

 suit the needs of Trypoxylon clavatum. Pupal cases" in situ. Natural 

 size. 



They work when burrowing in a very characteristic and 

 mechanical manner. Of course we could not see their 

 method of cutting the wood, but they get their load of saw- 

 dust in the depths of the burrow, emerge backwards and fly 

 away backwards a few inches frorr; the mouth of the hole, 

 hover or poise on the wing for some seconds until they 

 drop the load, ofttimes going mechanically straight to the 

 hole again, and sometimes turning the body slowly around 

 and flying in a circle, which of course makes a very stiff and 

 ungraceful movement, and then returning to the hole. 



A number of these little wasps were found living, in a 



