12S 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE, 
knob in the centre, from which fine lines radiate to the 
circumference of the gall. They are otherwise quite like 
the surface of the leaf. They are formed early in sum¬ 
mer; the insects (male and female) emerge in the beginning 
of July; and the galls thereafter become straw-yellow in 
colour, and are, therefore, much more conspicuous than 
before. 
Andricus marginalia Schlecht. Under this name has 
been described a gall that occurs commonly in many places 
in Scotland on oak-leaves, attached to the side of the mid¬ 
rib, and causing a break in the leaf-blade at such places. 
There is good reason to regard it as a variety of the 
gall of Andricus quadrilineatus Hart., found in the typi¬ 
cal form attached to the male catkins. It is identical in 
appearance and structure with the latter; hence a fuller 
description need not be entered on here. 
The next group of oak-galls, viz., those on the male 
catkins (therefore modifications of the stamens), is less 
numerous than the last. 
Andricus aistivalis Gir. has been recorded by Mr 
Cameron from Ardlui, as of rare occurence. The galls are 
crowded together on a short thick flowerstalk, in such a 
way as to resemble a mulberry, the mass reaching as much 
as lj-inch in length by over an inch in breadth. 
The separate galls are wedge-shaped at the base, and 
polygonal from mutual pressure, and may reach nearly 
i-inch in length by J-inch in greatest breadth. The 
apical part of each is free, and ends in a kind of cup with 
an irregularly lobed margin. They are greenish-yellow, 
or red. The centre of the cup is filled with a woody 
mass, in which are some cavities for larvae. The galls are 
formed in early summer ; and the insects (male and female) 
emerge in July. 
Andricus ramuli L. is the maker of very conspicuous 
galls on the catkins, strikingly similar to balls of white 
cotton, from ^-inch to 1 inch in diameter. A closer 
examination shows that this mass is made up of a large 
number of galls, about the size of a seed of the com¬ 
mon whin, thin-walled, hard, and each covered with a 
coat of long, dry, twisted flattened hairs like cotton 
fibres. At times isolated galls may be found on the cat¬ 
kins. They are formed in May and June, and the insects 
appear in July, and include males and females. The dis¬ 
tribution of this gall seems somewhat arbitary. It is 
common in various places along the Dee, near Aberdeen, 
and Mr Cameron records it from Strathglass. [It has 
been found on trees on the North Inch of Perth.— Editor.] 
Andricus amenti Gir. forms very inconspicuous galls, 
hardly more noticeable than the stamens among which 
one finds them. They are ovate, not exceeding l-12th- 
inch in length by half as much in breadth; and are 
marked with a slight furrow down the middle on each 
surface. They are brown, covered with very short stiff 
hairs, and very thin-walled. There are usually several on 
each catkin. As with the other catkin-galls, they are 
developed in May and June, and the insects (male and 
female) emerge in June and July. These galls are far 
from rare at Ballater on Deeside; they have been recorded 
by Mr Cameron from Rannoch; and Dr White sent me 
specimens from near Dunkeld some years ago. 
Andricus quadrilineatus Hart, is very common near 
Aberdeen. I have found the galls in Forfarshire and 
in Perthshire, and Mr Cameron records them as common 
near Glasgow. They show a considerable degree of vari¬ 
ability in form and markings, especially when dried ; and 
several of these forms have received names as distinct 
species, besides A. marginalis already noticed. In the 
typical condition they are attached to the male catkins, 
usually four or five on each. The usual form is oval, 
and the usual size about J-inch by J-inch. The sur¬ 
face is smooth, green, or green with red streakings, and 
faintly striated, or with no markings while fresh. On 
drying, the fleshy outer part of the wall shrinks on the 
ridged woody inner gall, and thus ridges appear on the sur¬ 
face forming a network, the arrangement of which has 
been employed to distinguish the supposed species from 
one another. The galls are formed in May and June; and 
the insects (asexual exclusively) emerge in the following 
spring. 
The only other oak-gall formed by a gall-fly that has 
been recorded as Scottish is found in the fruit. 
Andricusglandium Gir. attacks the acorns, but does not 
cause any marked external deformity in them. On cut- 
tiog open a galled acorn one finds in the interior a number 
of cavities of an oval or polygonal form, and about the size 
of whin-seeds, each enclosed in a thin hard walk Mr 
Cameron records these galls from Cadder and from Ardlui. 
The same species forms galls on Quercus Cerris on the Con¬ 
tinent and in England. The larvae remain in the galls for 
.years after they are gathered without undergoing any 
change. 
If now an analysis be made of the galls just described, 
it will be found that they may be divided into two great 
groups. First, those that appear in spring or early summer, 
and from which the insects emerge usually in the months 
of May, June, and July ; and second, those that appear 
only in autumn, become developed before winter, and fall 
to the ground, on which they pass the winter, often in¬ 
creasing in size for a time. From these latter the in- 
