186 Notes and Comments. 
of this insect, its habits, and relation to disease, has thus 
been rendered very desirable, and this difficult task the author 
has undertaken with great success. 
ITS CONTENTS. 
There are chapters dealing with the Structure and Habits 
of the House-Fly ; The Breeding Habits, Life History and 
Structure of the Larva; The Natural Enemies and Parasites 
of the House-Fly ; Other Species of Flies frequenting Houses ; 
The Relation of House-Flies to Disease ; and Control Measures. 
The chapters are illustrated by a number of coloured plates 
very beautifully executed, and by a large number of illustrations 
in the text. As showing the enormous amount of literature 
on the subject it may be mentioned that the Bibliography takes 
up 36 pages. 
HIBERNATION OF ‘MUSCA DOMESTICA.’ 
The author goes very fully into the question of hibernation 
of the House-Fly. The disappearance of flies towards the end 
of October and during November is a well known fact and the 
question is frequently asked, what becomes of them? To 
this disappearance three causes contribute, namely, retreat 
into hibernating quarters or into permanently heated places, 
natural death and death from the parasitic fungus, Empusa 
musce. The natural death of flies he considers may be com- 
pared to the like phenomenon that occurs in the case of the 
hive-bee, Apis mellifica, where many of the workers die at the 
end of the season by the fact that they are simply worn out, 
their function having been fulfilled. 
BAT PELE Ss: 
The flies which die naturally have probably bred for many 
weeks or months during the summer and autumn, and in the 
case of the females have deposited many batches of eggs ; 
their life work, therefore, is complete. Those flies which 
hibernate are the most recently emerged, and therefore, the 
youngest and most vigorous. On dissection it is found that 
the abdomens of these hibernating individuals are packed with 
fat cells, the fat body having developed enormously. Mature 
spermatozoa have been found in hibernating males. In some 
females it was found that the ovaries were small and in others 
very well developed. 
s1Ore 
The Proceedings of the Liverpool Naturalists’ Field Club for 1914 
(84 pages) contain Mr. J. W. Ellis’s account of the Field Meetings, which 
is mostly botanical; and Part 4 (Conclusion) of ‘ Wirral Fungi,’ by the 
same author. 
The Transactions of the Entomological Society of London, issued 
April 21st, contain the presidential address of G. T. Bethune-Baker, 
which deals with ‘ The Development of Clasping Organs in Insects.’ It is 
remarkably well illustrated. 
Naturalist, 
