116 THE INSECT WORLD. 
its body diminishes perceptibly, and the poor animal dies, like a 
fish taken out of its natural element. 
The insects which live in this froth are six-legged grubs 
(Fig. 84), which, when the froth is cleared from 
them, walk quickly enough on the stalks and leaves 
of plants. They are green, with the belly yellow. 
De Geer wished to know how they produced this 
singular froth, and found out in the following man- 
ner :—He took one of them out of its frothy dwelling, 
wiped it dry with a camel’s hair pencil, and placed 
Sear * Gt on a young stalk, recently cut from the honey- 
rina. suckle, which he put into water in a glass, in order 
to preserve its freshness, and this is what he observed :— 
“Tt begins,” says the Swedish naturalist, “ by fixing itself on a 
certain part of the stalk, in which it inserts the end of its trunk, 
and remains thus for a long time in the same attitude, occupied 
in sucking and filling itself with the sap. Having then with- 
drawn its trunk, it remains there, or else places itself on a leaf, 
where, after different reiterated movements of its abdomen, which 
it raises or lowers and turns on all sides, one may see coming out 
of the hinder part of its body a little. ball of liquid, which it causes 
to slip along, bending it under its body. Beginning again the 
same movements, it is not long in producing a second globule of 
liquid, filled with air like the first, which it places side by side 
with, and close to, the preceding one, and continues the same 
operation as long as there remains any sap in its body. It is 
very soon covered with a number of small globules, which, coming 
out of its body one after the other, tend towards the front part, 
aided in this by the movement of the abdomen. It is all these 
e'lobules collected together which form a white and extremely fine 
froth, whose viscosity keeps the air shut up in the globules, and 
prevents its froth from easily evaporating. If the sap which the 
larva has drawn from the plant is exhausted before it feels itself 
sufficiently covered with froth, it begins afresh to suck, until it 
has got a new and sufficient quantity of froth, which it takes care 
to add to its first stock.” * 

* « Memoires pour servir 4 |’ Histoire des Insectes,”’ tome iii. 
