EDW. JACOBSON, PLANIPENNIA FROM JAVA. 101 
The pygidium is used by the insect during its larval life 
to attach itself to smooth surfaces, by the aid of a sticky 
fluid, excreted at its tip. This proceeding can easily be watched 
from the back of a glass plate, on which the insect is made 
to move. When irritated, the larva likewise exeretes a drop 
of this fluid, which can be drawn out into threads. Most 
likely it is produced by the same glands that furnish, later 
on, the silk for the cocoon, which is spun by the aid of the 
pygidium. 
The larvae are of voracious habits. Some small Ephemeridae, 
which I provided for them, were immediately attacked and 
sucked dry. Most larvae were constantly running about in a 
hurry, covering their bodies with all sorts of small debris 
they could find. as pieces of egg-shells, fibres, and the skins 
of their victims. They took up this refuse with their mandi- 
bles, then, throwing back their heads, they deposited it on 
the bristles of their backs. Probably these objects only hold 
on by force of adhesion, as they are not fastened in any way, 
neither by threads produced by the insect itself, nor by the 
sticky fluid, excreted from the pygidium, of which fact I con- 
vinced myself repeatedly. With a small brush the objects, 
accumulated on the back of the insect, could easily be remo- 
ved, and showed no trace of being stuck on. I once observed 
a larva putting pieces of a spider’s web, which it found ona 
leaf, on-to its back, and I presume, that this habit has led 
some observers to the wrong conclusion, that the insect fas- 
tens the curious covering to its back with the aid of its own 
spinning threads. 
On the evening of the first and second day after hatching, 
all the larvae returned to the egg-shells on the stalks, and 
rested there in the attitude above mentioned. 
On October 12% they refused to accept food, became sluggish, 
and moulted on the 13". After each ecdysis their appetite 
seemed to increase, and I had work enough to provide for 
