SOLITARY WASPS OF GENUS SYNAGRIS ROUBAUD. 519 



that the female &'. cornuta possesses the power of regulating the 

 time of laying her eggs or at least of retarding the process consider- 

 ably for the benefit of the larva which she nourishes and cares for. 

 She devotes herself to it entirely and does not abandon it in spite of 

 the slowness of its evolution until she knows that it no longer needs 

 her services. 



In this particular case the retardation produced by the parasite in 

 the development of the first larva proved fatal to the whole subse- 

 quent progeny. The mother Synagris, after having finally walled 

 up the first cell, commenced the construction of the second nearly 

 three and a half months after the former. After a day of toil she dis- 

 appeared and did not return. It is probable that she perished 

 through accident and with her all the future line. This was the in- 

 direct result of the action of the parasitic ichneumon-fly on the first 

 larva, which occupied uselessly in its behalf the greater part of the 

 life of the female. 



It is possible, of course, that the latter, warned by the presence of 

 the parasite, summoned courage to begin a new nest elsewhere, but 

 the fact that she had commenced to build a second cell (at the origi- 

 nal nest) renders this hypothesis improbable. 



The duration of the pupal stage in S. cornuta is approximately a 

 fortnight. From one cell, which was closed on December 13, an 

 adult emerged on January 5 — after 23 days. It is necessary to 

 deduct from this period the time necessary for the larva to spin its 

 cocoon and transform itself into a pupa, which may be reckoned 

 as about a week. In order to escape from its prison of earth the 

 adult Synagris moistens with saliva, in the usual manner, the ball of 

 earth which closed the cell, and the latter, softened immediately by 

 absorption, yields at once to the pressure of the captive wasp. 



The males. — Following in this respect the habits of other Hymen- 

 optera, the males of Synagris cornuta take no part in the protection 

 or construction of the nest or in the rearing of the young, notwith- 

 standing the threatening armor of their mandibles. However, they 

 do not remain entirely ignorant of what passes; they inspect the 

 young and visit them daily. Under the roof of a hut at Brazzaville 

 Mr. Weiss and I noticed several nests of Synagris fixed in different 

 places and sufficiently difficult to find to require search for some 

 moments in spite of certain indications. One day I noticed a large 

 male of this species which flew about slowly, examining the nests 

 successively, moving with certainty and without any hesitation 

 toward each of them as if it had known for a long time the exact 

 location of each. It stopped for a moment on a nest, disregarding 

 the open cells and touching and examining preferably the cells still 

 Availed up, which contained pupae. This male evidently came to 

 watch the emergence of the young females, and the exact knowledge 



