1922] Taylor — Biology of Wasps of Genus Ancistrocerus 4-9 
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 isshownbythe 
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 kindly 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 my notice. 
