SOLITARY WASPS OF GENUS SYNAGRIS ROUBAUD. 517 



The nutritive paste is deposited by the mother wasp on the ventral 

 surface of the thoracic segments of the larva. A slight movement of 

 the head suffices to enable it to reach the food. The larva lies on its 

 back in the cell, and the form of its body, which is more sharply 

 curved than that of the species of Synagris (pi. 4, fig. 1), helps to 

 facilitate the contact of the mouth with the food. 



The solicitude of the mother Synagris for her offspring is very 

 great. She goes almost constantly in pursuit of food, which the larva 

 devours at once. During the day her hours of rest are few, for the 

 growth of the larva is rapid and its appetite insatiable. Hence one 

 sees the female at the nest only at short intervals. She brings food, 

 deposits it in the proper place, remains a few moments engaged in 

 caring for the larva, with the hind part of the body directed outward, 

 turns around, and leaves the nest once more. While she distributes 

 the food she does not appear to manifest her agitation and concern by 

 strokes of the wings, as Icaria or Belonogaster do when giving food 

 to their young. 



Nothing from without shows the nature of the occupation of the 

 Synagris when she provides for the needs of her larva. The absences 

 of the female when the larva is full grown are of frequent occurrence 

 but short duration. The extent of her wanderings and the radius of 

 her pursuit of prey must therefore be quite limited. During rare 

 moments of rest and at night the wasp remains in her cell with her 

 head turned outward, guarding her young. 



It would be interesting to know how the Synagris kills the cater- 

 pillars which she distributes to her larva, what use she makes of her 

 sting, and the primitive practice of paralyzing the prey. I was not 

 able to solve these questions. As to the nature of the caterpillars 

 which she captures, it is difficult to determine the species from the 

 food paste itself. However, as far as I was able to judge from the 

 form of certain parts of the anal region still recognizable, as well as 

 from the green color of the mass, they are probably skippers (Hes- 

 peridas), like those chosen by the other species of Synagris. 



When the female has decided that the growth of the larva is fin- 

 ished, she walls up the orifice of the cell with earth, and, ceasing 

 thereafter to occupy herself with the prisoner, thinks immediately 

 of the offspring which should succeed him. She goes back to the 

 original work of mason and builds at the side of the closed cell a 

 new one of the same type, which is immediately joined to the former. 

 Afterwards a secondary coating is used to consolidate the whole 

 structure, especially if the cells are already numerous. Their indi- 

 viduality is thus obscured. 



The new larva which hatches in this cell is nourished in the same 

 manner as before. In the meanwhile the preceding larva, in his 

 walled-up cell, after remaining inactive for some days, covers the 



