88 
BRITISH GALLS 
change their form as growth progresses. A remarkable 
feature of these insects is the enormous amount of secretion 
from their bodies. In some it is solid, as in Psylla buxi , 
where it forms a very long string attached to the body ; in 
others it is downy or waxy ; and in not a few it takes the 
form of “ honey dew,” which is always so attractive to ants 
and wasps. 
Psylla buxi attacks the apical shoots of the Box; the leaves 
become deformed and bent into a hemispherical gall resem¬ 
bling a cabbage in miniature. Trioza rhamni causes shallow 
depressions on the lower surface of Buckthorn leaves. 
A well-known Psyllid gall is that caused by Psyllopsisfraxini 
on the leaves of the Common Ash. We found them in great 
abundance in June, 1910, in the large wood above Weston- 
super-Mare, and in the Ash plantations on the limestones in 
other parts of Somerset. Usually only one-half of the leaf 
is involved, generally towards the apex. The infected parts 
assume a light yellow tint, and are traversed by swollen 
reddish veins, presenting a pretty reticulated appearance. 
In PlateXII., Fig. 1 (a) shows a gall in an early state, ( b ) a 
mature gall, ( c ) an old and broken one. Figs. 2 to 4 show 
the Psyllid in various stages of development. 
The only insect gall that I am acquainted with on our 
native Rushes is caused by the Psyllid Livia juncorum. It is 
very distinctive. At maturity it resembles a tassel, and is 
usually situated at the apex of the stem. It consists of a 
variable number of stunted green blades springing from the 
widened sheath of the shortened stem. The galls that are 
in the blade are yellowish, but those which catch the sun¬ 
light are beautifully tinted with red. They are not uncommon 
on various species of Juncus on the margins of large ponds 
in the southern counties—for instance, Frensham Pond, 
in Surrey. 
We now come to the last family of the British gall-caus¬ 
ing Homoptera—namely, the Coccidae. The minute insects 
which comprise this family are popularly known as scale- 
insects or mealy-bugs. All excrete matter which forms a 
