Mr. Withycombe on Infe-history of Boreus hyemalis. 313 
the female, which is completely apterous except for a pair 
of small scale-hke lobes on the mesothorax. The male 
has two pairs of curved bristle-like wings. Each anterior 
wing is stiff and covered with spines. On its hind margin 
it is grooved and acts as a covering to the hind-wing, 
which is much less hairy and not so strongly chitinised. 
The abdomen of the male is curved upwards at the apex 
and bears the complex genitalia. The posterior dorsal 
margin of the second abdominal segment in that sex is 
produced upwards into a small erect lobe, which is obliquely 
truncated, appearing as a small forwardly directed ridge 
when viewed from the side. In the female there is a long 
Ovipositor giving the insect somewhat the appearance of 
a female Locustid. A point of interest about the adult is 
the presence of a peculiar sieve of chitinous, doubly grooved 
bristles in the proventriculus, as is also found in other 
Mecoptera, in the flea, and in crickets. 
On first escaping from the pupa the colour is greenish 
yellow, but in a day or so this darkens, the back and sides 
of the head, thorax and abdomen becoming bronzy brown 
or bronzy green, the rest of the body including rostrum 
being yellowish brown. 
Length about 3 mm.; of female with ovipositor 5 mm. 
In November the insects may be found running about 
on the surface of moss, often in numbers. They are, how- 
ever, very local, and may be found in plenty on a patch 
of moss six feet across, while another patch a few yards 
away is totally devoid of specimens. 
Normally it runs slowly about, but on being disturbed 
‘ jumps six inches or more, then usually lying still for a 
minute or so before resuming its perambulations. It is 
quite active in pouring rain, but I have never seen it 
above the snow. I went twice to localities in which I 
knew Boreus to occur, one day, and two days after a fall 
of snow (four inches approx.), and each time found no 
insects running on the snow. I am not aware that it is 
distasteful to birds, but should it possess no obnoxious 
properties one would expect it to be speedily devoured 
under such circumstances. Both robins and tits were 
much in evidence on these occasions. I have never ob- 
served any offensive smell to be given off by the insect, 
but once on irritating one (female) I noticed a somewhat 
nutlike odour similar to that given off by some species of 
Polydesmus. 
