ON THE HABITS AND LIFE-HISTORY OF LEUCOSPIS 
AFFINIS (SAY). A PARASITE OF BEES. 
By S. Graenicher. 
J. H. Fabre ( i ) has presented us with a very detailed account 
of the habits of the European Leucospis gigas, a parasite of two 
species of mason-bees of the genus Chalicodoma, and further on I 
shall compare his results with those obtained from a study of our 
species, L. affinis. 
My first acquaintance with the larva of Leucospis affinis, a 
Chalcidid parasite of bees of the genus Osmia was made from a 
nest of Osmia pumila Cr., collected at Cedar Lake, Washington 
Co., Wis., September 27, 1903. The nest was situated in a dead 
branch of an elder, and contained two cells placed longitudinally. 
One of the cells contained a male specimen of the bee ready to 
leave the nest, but still enclosed within its cocoon. It may be 
stated in this respect that in this, as well as in the two additional 
species of Osmia to be considered in this paper (O. atriventris Rob. 
and O. simillinia Sm.) the bees reach the imago-stage in the fall, 
but pass the winter inside of their cocoons, and leave the nest in 
the spring. The same has been reported for several species of 
Osmia of Europe, the habits of which are known. 
The second cell of the nest of Osmia pumila under considera- 
tion harbored a full-grown larva of the parasite Leucospis affinis 
inside of a cocoon (spun by the Osmia-larva) , and this pupated 
on May 28th of the following year, and made its appearance as an 
imago on June 27th. 
In an additional nest of the same species from the same locality 
found in the dead stem of a sumac, altogether four cells were 
present, and three of these were infested by Leucospis affinis. At 
the time the nest was opened (July 31, 1905,) the parasitic larvae 
were already fully developed, but they too passed the winter in 
the larval stage. 
From a nest of Osmia atriventris in a piece of dry bark (Cedar 
Lake, July 31, 1905,) two larvae of this same parasite were 
obtained. 
1. J. H. Fabre, Souvenirs entomologiques, Vol. Ill, pp. 154-177, pp. 
212-218. 
153 
