Mr Brindley, Notes on the Breeding of Forficula auricularia. 335 
Notes on the Breeding of Forficula auricularia. By H. H. 
BRINDLEY, M.A., St John’s College. 
[ead 17 November 1913] 
IN a previous paper* I summarised what is known with 
regard to the oviposition, hatching and the duration of the imma- 
ture life of the Common Earwig. It was mentioned that no record 
could be found of this species being raised to maturity from the 
egg in captivity, and that Mr Potts and myself had failed to do 
so with eggs laid by earwigs brought to Cambridge from the Farn 
Islands in 1907 and 1908. 
In October 1912 I received a large number of living adults 
from Round Island, Scilly Isles. They were collected in September, 
and probably most of the females had paired, for while searching 
Gunwalloe Cove on The Lizard, in the same month of 1912, it was 
very common to find a male and a female together under stones. 
About 110 females were isolated in plaster of Paris cells 
averaging 24 in. wide by 14 in. deep, and covered by watch glasses. 
20 more were isolated in flower pots. In an endeavour to diminish 
the risk of septic infection and attack by fungi, coconut fibre was 
the only substance used for lining the cells and flower pots. The 
coconut fibre was kept fairly damp and as far as possible uniformly 
so. A small piece of washed potato without any skin adhering was 
the only food given, and this was renewed twice weekly. This 
diet was suggested by the quantity of potato peelings in the light- 
keepers’ rubbish heap from which the earwigs were captured. 
All the cells and flower pots were kept in a room in the 
Zoological Laboratory, Cambridge, as far,as possible from the hot 
air supply, though the temperature was on the average consider- 
ably above the winter temperature in the open on the Scilly 
Islands. The isolated earwigs were somewhat sluggish and did 
not eat the potato slips much. Some hid under the latter, some 
buried themselves first below the surface of the coconut fibre, 
while a good many remained on its surface. 
It was not possible to examine all the cells daily, but an 
endeavour to look at all at least twice a week was made. So the 
days which follow should no doubt in many cases be slightly ante- 
dated. Counting the number of eggs in a clutch was rather 
neglected, in the fear that much disturbance of the heap in which 
they were laid might diminish the chances of hatching. 
* Proc. Camb. Phil, Soc. vol. xvi. part 8, 1912, p, 674, 
