of Forficula auricularia in the Scilly Islands. 333 
and came away with the conviction that its earwig population 
is sparse. The sketch map renders it unnecessary to particularise 
other instances of the same kind. The thought arises as to 
how long the Scilly Islands have had their earwig population. 
The mainland is 25 miles away at its nearest, and though the 
Common Earwig hardly ever uses its wings it is conceivable that 
individuals have been blown across from Cornwall now and then. 
But an earwig with furled wings, though it readily drops in order 
to seek shelter, is not easily blown from a spot it intends to hold 
on to. Floating vegetable matter and soil on the feet of birds 
may have helped to introduce earwigs into the islands along with 
other non-flying invertebrates, such as woodlice and earthworms. 
Probably, however, man has been an important factor in carrying 
earwigs to the Scilly Isles: their habit of concealing themselves in 
folded clothes and in crevices of all kinds greatly assists their 
passive transport. We do not know how long ago man settled on 
the larger islands, one can say no more than that his arrival was 
pre-historic. With regard to Round Island and Rosevear the 
suggestion may be hazarded that the extraordinary abundance of 
earwigs they possess may be partly the result of recent human 
settlement. On Round Island there is little doubt that they 
find abundant nourishment in the light-keepers’ rubbish heap, 
but on Rosevear there has been no such food supply for more 
than sixty years. I am unable to say anything as to what the 
Rosevear earwigs feed on at the present time. It is striking 
that these two islets should stand out as inhabited by earwigs 
with large bodies and great frequency of “high” males, while 
the numeérical proportions of the sexes differ so much. It does 
not appear likely that food more varied than the wild vegetation 
is a cause of the greater size, for in the Farn Islands in 1907 
Mr Potts and myself found that earwigs from the two unin- 
habited Widerpens were larger than those caught on the Inner 
Farn, which at that time had a poultry farm as well as the light- 
keepers’ houses. Again, on Tresco, the specimens from New 
Grimsby were large while those from the Abbey Gardens com- 
paratively small, both were living near human habitations but 
in different conditions as regards vegetation and soil. No more 
can be said with approach to certainty than that the specimens 
obtained from cultivated ground were generally smaller than those 
from rocky and wild localities. It may well be that local races 
are in process of evolution. The absence of earwigs on Annet is 
peculiar. Our search was sufficiently thorough to convince us that 
either earwigs have not obtained a footing there or that they 
exist in quite small numbers in isolated spots. Its nearness to 
a large island well stocked with earwigs and its vegetation gave 
the expectation that plenty would be found. This island furnishes 
