1922] Taylor — Biology of Wasps of Genus Ancistrocerus 49 



been possible to keep in close touch with the operations of nest 

 construction and also to observe the development of egg, larva 

 and pupa. 



About the middle of June sixty artificial nesting places were 

 put out on the window sills and in other situations near the walls 

 of the Bussey Institution where Eumenids had been noticed 

 searching for places in which to nidificate. These nesting places 

 were crudely and variously constructed, all, however, consisting 

 of glass tubes inserted in holes bored in blocks of wood. A type 

 of the apparatus used is shown in figure 1; others were more 

 simple, but all were so constructed that the tube could be ex- 

 peditiously removed and replaced. It was found by trial that 

 tubes having an inside diameter of from six to eight millimeters 

 were preferred by the wasps. Individuals repeatedly entered 

 and examined tubes of greater diameter, but in no instance did 

 they make use of them. 



That these tubes were acceptable to the wasps is shown by the 

 fact that no less than three started their building within the 

 first three days after the tubes were placed out, one nest having 

 been entirely completed during that time. The device proved 

 to be convenient for the study of the occupants but for two 

 disadvantages. First, the condensation of moisture on the inside 

 of the glass tubes sometimes caused the egg or young larva to 

 adhere to the walls so that it was prevented from reaching its 

 food. The moisture also accelerated bacterial infection which in 

 some cases destroyed both egg or larva and provisions. Second, 

 the activities of the larva after the spinning of the cocoon could 

 not be well observed without breaking the tube. 



I wish to thank Doctor Joseph Bequaert of the American 

 Museum of Natural History who has very kindl}^ determined 

 the species of Ancistrocerus mentioned in this paper. 



Ancistrocerus tardinotus Bequaert MS. 



This species of Ancistrocerus is treated in detail, as I had the 

 opportunity to observe rather closely the nest-building activities 

 of two females. It will also serve as a type of the work done by 

 other Eumenids which came to mv notice. 



