8 
POPULAR SCIENCE REVIEW. 
two lame go on growing together till the cynips is ready to assume the pupa 
state ; then the parasite cuts the vital thread of the cynips and uses its skin 
for a pupal envelope for itself, and thus, instead of the gall-fly emerging into 
clay, a beautiful green insect makes its appearance on the stage of life. I had 
the pleasure of first discovering this parasite while engaged in studying the 
cynips ; it belongs to the genus Ccdlimome, and from the fact of having dis- 
covered it in Devonshire, I gave it the name of Callimomc Dcvoniensis. It 
is one of the handsomest of our British insects ; its costume a brilliant green, 
shot with gold ; the abdominal segments green, gold, and purple ; legs 
yellow ; tarsi reddish ; and it has four beautiful transparent and irridescent 
wings. 
It has been stated that oak-galls are produced at the expense of acorns. 
From this view, my experience leads me to dissent. In exceptional instances, 
it may have been the case ; but, as a rule, the cynips confines its attacks to 
young trees and young growths in hedges, within a range of ten or twelve feet 
from the ground, and the nearer the ground the more numerous the galls. 
Y oung trees which have not attained a greater height than that I have indi- 
cated, suffer so much, that many of them can scarcely make headway against 
their foe ; and in several nurseries I have visited, where it might be expected 
that greater care would be paid than in the case of ordinary plantations, the 
young stock of oaks has been rendered quite unsaleable by the pest. This 
year I have noticed the progress of the insect on two groups of young English 
and Turkey oaks growing side by side ; and although there are hundreds of 
galls on the English oaks, there are none on the Turkey oaks. From this I 
am led to infer that the species of cynips now under notice is confined in. its 
depredations to the English oak ; and as it invariably selects trees of younger 
or restricted growth — probably because the temperature at a higher elevation 
than ten or twelve feet from the earth is unfavourable to it — it would seem 
that children might be advantageously employed in young plantations in col- 
lecting the galls by means of cutting hooks, such as are used for thistles. The 
galls, when once collected, might either be crushed for tanning purposes, or 
consumed by fire, and if the process were repeated for two or three seasons, 
it is more than probable that the plantation would be altogether freed from 
the pest. 
These able remarks not only well describe the nature of the 
attack, but also point to a cure, a matter to which we would 
direct the most serious attention of the planter ; for we may 
state that, in 1853, we saw some very small oak trees, in the 
neighbourhood of Dawlish, Devon, from which some hundreds 
of these galls might have been gathered. This was the first 
time we had noticed this pest, though it appears that it had 
been under Mr. Parfitt’s notice as long as a dozen years. 
Since then (1853) we have traced it in its progress as 
follows : — 
Having observed the galls in Devon in 1853, we were yearly 
on the look-out in the Midland and Eastern counties for its 
appearance, and the following dates will show that its spread, 
though gradual, was sufficiently rapid : — 
