SOLITARY WASPS OF GENUS SYNAGRIS ROUBAUD. 511 



there was a larva of large size with a provision of seven caterpillars, 

 two partly devoured. 



With the aid of the foregoing data, it is possible to contract a 

 history of this Synagris. The wasp lays an egg in its cell of earth. 

 Then, without haste, after having guarded it for some time, com- 

 mences to collect a small provision of caterpillars for the moment 

 of hatching. When the larva has commenced to feed, the Synagris 

 continues its provisioning, but in a slow and regular manner, taking 

 care only to furnish its larva with a little more food than is neces- 

 sary for the day. It is a progressive provisioning, from day to 

 day, which gives the wasp the necessary leisure to guard the larva 

 and watch its growth. A fact of this kind has never before been 

 recorded of the solitary wasps. 



When the larva has attained three-fourths of its size, the wasp 

 incloses it in its cell with the last provision. At this time the larva 

 is still transparent and rose colored. In three days it devours the 

 caterpillars at its disposal, takes on a uniform yellowish color, and 

 loses its transparency on account of the abundant development of 

 reserve nutriment. After three days of rest, during which it remains 

 inert and without movement, it spins the thin walls of silk which 

 surround it, and outside of which are left the alimentary wastes, the 

 excrement of the caterpillars, and the hard chitinous parts which 

 have not been devoured. 



From 19 to 23 days intervene from the time when the larva spins 

 its cocoon to the time when it emerges as the adult insect. The pupa, 

 properly so called, exists for about 12 days. Thus, three larva 1 

 which spun their cocoons on February 19, 22, and 23, respectively, 

 were transformed into pupae on March 1, 3, and 5. The adults came 

 out on March 10, 15, and 18. The duration of the pupal stage was, 

 therefore, 10 days for the first, 12 days for the second, and 13 days for 

 the third. 



. The caterpillars which the female wasps choose for the nourish- 

 ment of their larvse are those of various species of hespericls (skip- 

 pers). I did not observe either their capture or the method of ren- 

 dering them immobile. Some of them were bitten on the side of the 

 head, and the majority showed indications of having been stung sev- 

 eral times. They were always more completely immobile than the 

 caterpillars made use of by the solitary wasps of the genus Odynerus 

 in our country. Fabre has observed as regards the latter that the 

 caterpillars, although stung, do not remain motionless, and that they 

 would crush the egg by their movements if it were deposited in their 

 midst. Hence the utility of the suspensory thread which attaches 

 the egg to the surface of the cell in different species of Odynerus and 

 Eumenes. Ferton mentions that in the case of nests which he ob- 

 served the caterpillars were possibly able to spin cocoons and to trans- 



