THE BIOLOGY OF THE MUD-DAUBING WASPS 



AS REVEALED BY THE CONTENTS OF 



THEIR NESTS 



PHIL RAU AND NELLIE RAU 

 Saint Louis, Mo. 



With five plates 



This paper is primarily a study of the contents of the nests 

 of three species of mud-daubing wasps. Before entering upon 

 a discussion of how the nests are provisioned and how the young 

 fare in their struggle against adversities and enemies, it will 

 be well to become familiar with the nests themselves, their 

 structure, their sites, decorations, etc. 



Fossorial Hymenoptera are roughly classified, according to 

 their habits, in four groups: 1. Those which build no special 

 receptacles for their young but are either parasitic or subparasitic, 

 or take advantage of the abodes of other insects, holes, etc.; 

 2. Builders of cells in the form of pottery constructed of clay 

 mixed with water or saliva and dried; 3. Excavators of burrows 

 in the ground; 4. Makers of tunnels in wood or the stems of 

 plants. 1 



The three species of Fossorial wasps herein dealt with belong 

 to the second group of this classification, those wasps which 

 construct cells of clay or mud as receptacles for their young 

 and its provisions. The mothers themselves do not use these 

 structures for their own shelter, but go elsewhere for the night. 

 All three of these species are spider ravagers. 



First we have the pipe-organ type of mud nests (see figs. 

 1, 2, 5) built by Trypoxylon albitarsis Fab., the shiny black wasp 

 with beautiful white toe-tips. Then we have the familiar mud 

 nests which at first sight look like a clod of earth; these are 

 made by two species belonging to the subfamily Sceliphroninae, 

 Sceliphron (Pelopoeus) caementarium Drury, a pretty black wasp 

 trimmed up in yellow (this wasp is commonly known by the 

 boys in my neighborhood as "yellow-legs"), and the beautiful 

 steel-blue wa sp, Chalybion caeruleum Linne. The nests of these 

 1 Sharp, D. Insects, Pt. II. Cambridge Nat. Hist., p. 90. 



