132 SOCIAL HABITATIONS. 
“The most remarkable circumstance in the case in 
question, was the apparent inability of the grub to con- 
struct a fresh cell after the first was injured,—proving, 
we think, beyond a doubt, that it is the puncture made 
by the parent insect when the egg is deposited that 
causes the exudation and subsequent concretion of the 
juices forming the gall.” Although the insect in question 
succeeded in attaining the perfect state, it would probably 
be of stunted growth in consequence of the deprivation 
of food. Such, at all events, is the case with insects of 
other orders, when their supply of food is at all checked 
while they are in the larval state. 
There is another weevil which is one of the gall- 
makers. It is one of the largest of the British weevils, 
being more than half an inch in length, and is very 
simply clad in grey and black. 
If the reader desires to discover the larva of the beetle 
he may probably be successful by going to any waste 
spot where thistles are allowed to grow, and examining 
them carefully about the stems and roots. Nothing is 
more common than to find the stems of thistles swollen 
in parts, and in many cases the root is affected as well 
as the stem. Fortunately for the gardener, who hates 
thistles, even though he should be a Scotchman, as is so 
often the case with skilled gardeners, the larva of the 
Cleonus feeds on the juices of the plant at the expense 
of its life, so that the thistle dies just before the seed is 
developed, and a further extension of the plant is thereby 
prevented. 
There are also gall-making insects among the Diptera. 
Such, for example, is the THIsTLE-GALL Fiy, which pro- 
duces large and hard woody galls upon the thistle, as 
