


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, 
Ai lane, it on a young stalk, recently cut from the honey- 
(Cercoprs spumaria). 1 11e which he put into water in a glass, in order 
to preserve its freshness, and this 1s what he observed :— 
“Tt begins,” says the Swedish naturalist, “by fixing itself on al 
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 ball o: 
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 1 
very soon covered with a number of small balls, 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 thes 
balls collected together which form a white and extremely fim 
froth, whose viscosity keeps the air shut up in the globules, anc 
prevents its froth from easily evaporating. If the sap which th 
nympha has drawn from the plant is exhausted before it feels itsel| 
sufficiently covered with froth, it begins afresh to suck, until i 
has got a new and sufficient quantity of froth, which it takes cari 
to add to its first stock.’’* 
* “Mémoires pour servir a l’ Histoire des Insectes,’’ tome iii. 

