510 ANNUAL. EEPORT SMITHSONIAN INSTITUTION, 1910. 



a Synagns obtained its materials at the expense of fresh nests that 

 were still occupied. The nests were 8 to 9 centimeters long and 7 

 centimeters broad ; the height of the cells, 4.5 centimeters. 



Association of nests. — Sometimes the nests are associated, several 

 being placed side by side, so that they form bands of earth 20 to 25 

 centimeters long, according to the number of individual nests. The 

 number can be ascertained by observing the constrictions in the mass 

 of earth which mark the area of contact between two different nests. 

 (PI. 2.) Are these fortuitous associations of nests of different age 

 grouped by adult wasps which had no original connection with each 

 other; or are they constructed by females born in the same nest? It 

 is difficult to decide. It appears, a priori, not impossible that they 

 represent the first step toward a grouping in colonies. 



Rearing of larvcB. — On February 19 I discovered under the roof of 

 a farm building a nest of this Synagris, with two cells. The older, 

 the orifice of which was walled up with a plug of earth, contained a 

 larva already well grown, and a provision of six inert caterpillars, 

 one of which was about three-quarters eaten. In the more recent cell, 

 which was guarded by the female, was found a single yellowish egg 

 merely placed in the bottom of the cell. On the 22d of February 

 another nest was pointed out to me by natives on the quarters of the 

 Senegal tirailleurs. I had it brought down with the greatest precau- 

 tions. It was an association of nests forming a band that measured 

 about 30 centimeters in length. The adults had already taken their 

 flight, as these nests were old. In two of the cells were found only 

 a couple of females, probably the builders, who had retired within* 

 them to die. The last cell alone, at one end of the assemblage, was 

 guarded by a living female. I found there an egg that occupied the 

 bottom of the cell and above it 5 large hesperid caterpillars. 



On the 23d of Februaiy a third nest was brought to me by a Ba- 

 kongo boy, who had obtained it on his quarters. Three cells were 

 walled up and contained a young pupa and two full-grown larvse. 

 A fourth cell was open and contained a wasp with its head turned 

 in a menacing attitude toward the opening. It had not abandoned 

 the nest, while the latter was being transported. On turning it out, I 

 found in the cell 10 large hesperid caterpillars, to serve as provision 

 for a large larva which had already attained three-fourths its full 

 size. 



On the 27th two nests were brought to me with the greatest care 

 by natives. One consisted of three cells, of which two were closed. 

 The third harbored a young larva with a provision of eight cater- 

 pillars. The other nest comprised five cells. In the freshest one, 

 which was guarded by the female, was found an egg without pro- 

 vision. In one of the adjoining cells, which had the orifice closed, 



