THE NATURAL HISTORY OF THE SOLITARY WASPS 

 OF THE GENUS SYNAGRIS.^ 



[Witli 4 plates.] 



By E. EouBAUD. 



The solitary wasps of the subfamily Eumeninae which belong to the 

 genus 8ynagris inhabit the whole of Africa except the northern por- 

 tion and Egypt. They are closely allied to the genus Rhynchium^ 

 but are distinguishable by the labial palpi, which have only three 

 joints, the very long labrum, and the maxillary palpi of 3, 4, or 5 

 joints.- 



The systematic relationships of this group, although elucidated by 

 the early investigations of Pe Saussure, are still imperfectly known, 

 while the biological data which we possess regarding them are much 

 more fragmentary. We know that these insects build nests in the 

 ordinary manner of the eumenids, but their larvae are little known 

 and their mode of feeding and their history still less. 



During the leisure hours of my sojourn in the Middle Congo as a 

 member of the commission for the study of the sleeping sickness, I 

 sought as far as possible to supply some of these deficiencies in our 

 knowledge. The wasps are quite common in the lower Congo, and I 

 found there three species, S. calida L., S. sicheliana Sauss., and the 

 most common as well as most remarkable of all, S. cornuta L. These 

 three species nest by preference on the roofs and walls of houses, at 

 all times, both in the dry or cold season and in the rainy or warm 

 season. There was, therefore, at my very door an interesting subject 

 and one relatively easy to follow and to study from a biological stand- 

 point. Since it had to do with the eumenids, one might have ex- 

 pected a mode of life but little different from that of other solitary 

 wasps — ^that is to say, an ordinary provisioning of the nests by means 

 of fresh paralyzed prey, with which the ^gg is shut up and left en- 



1 Translated by permission from Annales de la Societe Entomologique de France. 

 Paris, July, 1910. Vol. 79, Pt. I, pp. 1-21. 



2 1 owe all the bibliographical details, the information regarding classification, and 

 the exact identification of the species which are the object of these observations, to my 

 friend. Viscount R. du Buysson, whose knowledge and courtesy have been unfailing. I am 

 happy to express here my very sincere thanks. 



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