ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 31 
Parasitic Bees.'^ — Prof. E. Hoffer gives an account of the genus 
Psithyrus, the members of which are parasitic in the nests of humble^ 
bees, which they very closely resemble. The female may be distin- 
guished from a humble-bee by the less curved tip of the abdomen, by 
the raised ventral ridges which converge from the sides to the tip, by 
the absence of collecting ap|)aratus, by the somewhat naked and shining 
back, and by certain differences in labrum and mandibles. The males, 
which are much smaller than the females, may be distinguished from 
species of Bomhus by the relatively short head, by the externally convex 
and uniformly hairy tibia of the posterior legs, by the almost mem- 
branous and light-coloured genital appendages, and by several other 
characteristics. There are only male and female forms of Psitliyrus , — • 
the latter appearing in spring, the former decidedly later. After- 
describing the structure of the body, the author gives a very interesting 
account of the mode of life of both sexes. He describes the slow flight 
of the females in early spring, their sluggishness except in bright sun- 
shine, their deliberate and thorough robbery of a few flowers, and their 
determined search for Bomhus nests. An entrance is effected by force, 
but apparently only into those nests which contain either a solitary 
queen Bomhus, or only a few workers. The egg-laying of the Psitliyrus 
Avas not observed. Only the stored pollen and honey of the hosts are 
devoured by the adult parasites at least, but the consequence is always 
that the humble-bee colony ceases to flourish. It is j^ossible, or even 
probable, that the larvie of the Psitliyrus devour those of their hosts, 
but the mother probably superintends the nutrition of her larvee, and 
also forbids the entrance of other claimants. The lives of the males in 
the two genera are as similar as those of the females are different ; and, 
as in the case of Bomhus, the males of Psitliyrus all die in the cold and 
scarcity of food associated with the advent of autumn. Professor 
Holier describes six species of Psitliyrus from the Steiermark district. 
Parasitic Castration of Typhlocybse.f— M. A. Giard gives an 
account of his observations on the parasitic castration of Typlilocyha by 
the hymenopterous larva Aplielopiis melaleucus and the dipterous larva 
Atelenevra spuria. Like their hosts, these insects have two generations 
in the year. The researches of Mr. James Edwards show that what, in 
a previous note, M. Giard called T. rosse L. should be distinguished 
into T. liippocastani J. Edw. and T. Douglasi J. Edw. Aphelopus 
usually attacks the former and Atelenevra the latter. Parasitism by 
Aplielopms generally causes the ovijmsitor to be much reduced and in- 
capable of penetration, but Atelenevra seems to have much less influence. 
The penis, on parasitic castration, undergoes considerable reductions, 
and the specific character is greatly modified. 
Certain singular organs, hitherto overlooked in the males of Tijplilo- 
cyha, have the form of two invaginations of the ectoderm, which start 
from the ventral surface of the first abdominal segment, and extend, like 
the fingers of a glove, to the extremity of the fourtb segment ; these the 
author regards as homologous with the stridulating organs of the male 
Cicadas. When the males are parasitically infested the ventral invagi- 
* MT. Nat. Verein Steiermark, xxv. (1889) pp. 82-158 (1 pi.). 
t Comptes Rendus, cix. (1889) pp. 708-10. 
