516 ANNUAL. KEPORT SMITHSONIAN INSTITUTION, 1910. 



however, bring back any prey, nor undertake any provisioning of the 

 nest. It is only when the larva is hatched that the wasp begins to 

 hunt in a more active manner. She comes and goes incessantly, re- 

 maining about the nest only a very short time at repeated intervals. 

 In this respect the habits of our Synagns are entirely different, not 

 only from those of the two preceding species, but. also from all that 

 is known relative to the eumenids. In examining nests several times 

 shortly after the return of the female — which never appeared to 

 carry living prey in her mandibles — I always found them without 

 provisions of any kind. ^Vhatever might be the age and stage of 

 development of the larva, which lay on its back at the bottom of the 

 cell, it never appeared to have any caterpillars at its disposal. Fur- 

 thermore, no remains of a previous repast were found, either head 

 pa'rts of caterpillars previously devoured, or excrements of paralyzed 

 caterpillars, such as were always to be seen in the cells of other species' 

 of Synagris. One is led to conclude that S. cormda forms a re- 

 markable exception among solitary wasps as regards its habits, in 

 that it nourishes its larvse from day to day, without storing provision 

 for them, and doubtless in a very special manner. 



By observing more closely the goings and comings of these wasps 

 I secured the key to the problem. A nest easy of access was ex- 

 amined at the moment when the mother Synagns left a cell. I ex- 

 amined carefully the contents of the cell and found therein, as 

 usual, no trace of caterpillars. The larva of the Synagris lay at 

 the bottom of the cell. I grasped it lightly by the aid of pincers, 

 and after having confirmed the fact that it showed no trace of food 

 I replaced it in its normal position. Ten minutes later the wasp 

 returned, flying rapidly, and entered the nest. After waiting some 

 moments I forced it to leave the spot and then saw, deposited on the 

 thorax of the larva, on the lower surface near the mouth, a little 

 food mass of a green color and of semifluid consistency, which the 

 larva ate greedily. Looking a little closer, I saw that this food con- 

 sisted entirely of the rudely worked-up body of a caterpillar. 



The manifestation of the feeding instinct of this solitary wasp 

 proves to be entirely different from the stage at which it has arrived 

 in the other two species of Synagns. S. cornuta nourishes its larva 

 from day to day with caterpillars ground up into a paste which it 

 places close to the mouth of its offspring in the manner so well known 

 among the social wasps. 



Thus we find in this species no trace of the primitive provisioning 

 instinct of the solitary wasps. By a sudden leap, we pass to a mode 

 of rearing the larvae greatly more advanced, which indicates on the 

 part of this species a maternal care that reveals itself only in a very 

 indifferent and primitive form in Synagris sicheliana. 



