360 Proceedings of Royal Society of Edinburgh. • [sess. 
As regards insect and work, the two may he distinguished thus : — 
S. destructor is larger, measuring 4 to 6 mm., multistriatus being 
in length only 3 to 3J mm. The larvse of destructor are also 
larger, hence the mother gallery and the resulting larval tunnels 
are also of greater circumference. The larval galleries of S. 
destructor from each mother gallery are not so numerous nor 
so close together as those of S. multistriatus. 
Scolytus multistriatus. 
The beetle is black or dark brown, and glossy, the antennae 
and legs paler. The thorax is longer than broad and very finely 
punctured, the punctures on the flat part being finer and not 
50 thick as those at the sides. The brown elytra, somewhat 
narrowed behind, show many punctured striae. From the 
posterior margin of the second abdominal segment there projects 
a moderately long, strong spine, backwardly directed. In the 
male the forehead is somewhat compressed, and bordered at 
the sides and behind with greyish-yellow little bristles. In the 
female the forehead is somewhat arched and lacks the bristles. 
Length, 3 to 3J mm. 
After fertilisation and the boring into the bark of the elm, 
the female gnaws out in the cambial region a gallery, longitudinal 
in direction. This gallery cut out in the youngest wood-layer 
varies in length between one and two inches, measurement of 
some of the galleries in my experiment giving 1-J in., 1J in., 2 in. 
In shape the gallery resembles a miniature golf club, the head 
of the club marking the place of entrance and start. Along 
the sides of this neat gallery, the mother cuts little notches at 
equal distances from each other, and in each notch an egg is 
laid. The legless, whitish, brown-headed grubs on hatching out 
proceed to gnaw their tunnels at right angles to the parent 
gallery. These tunnels, crowded together, are cut chiefly into 
the bark, but where the bark is thin their course can be traced also 
on the outermost layers of the wood. As the tunnels run out from 
the parent gallery, they cease to be at right angles, but bend, some 
upwards some downwards, while the width of the tunnel keeps 
increasing with the growth of the grub. At the end of the larval 
tunnel (some of the tunnels in my specimens were 2J inches long) 
