TypHa Insects: THrEetrrR EcoLoGicaAL RELATIONSHIPS 505 
conditions. It inserts its eggs into the pappus, where they are hidden 
from all enemies and where the nymphs find an abundance of food at 
hand which is not contested by any close relatives and which, indeed, 
is used by few other insects. 
INSECT INHABITANTS OF THE LEAF OF TYPHA 
The inhabitants of the leaf comprise two classes, the surface feeders 
and the leaf miners. The surface feeders include, among the Lepidoptera, 
Arsilonche albovenosa, and among the Hemiptera, the Aphidae enumerated 
on page 501. The most common of the surface feeders is the noctuid 
caterpillar, A. albovenosa. It is a general feeder but is very commonly 
found on eat-tail. The eggs are placed on the upper part of the leaf, 
and the larvae, as soon as hatched, feed on the leaf. A leaf thus infested 
has the appearance of having been skeletonized. After they grow larger, 
the larvae begin feeding on the edge of the leaf, where they eat out large 
sections. 
The species of aphids mentioned on pages 500-501 may be classed as 
feeders on the leaf, although they occasionally feed lower down on the 
stem and sheaths of the plant. 
The leaf miners include Arzama obliqua Walk. and Nonagria oblonga 
Grote. These twonoctuid larvaedo not restrict themselves entirely to leaf 
mining but they begin their larval life as leaf miners, later becoming true 
stem borers. Although the two species are related, their habits differ 
ereatly. A. obliqua overwinters as a larva in its burrow in the cat-tail 
plant, whereas N. oblonga apparently passes the winter in the egg stage. 
The eggs of A. obliqua are laid in the spring, while those of N. oblonga 
are apparently laid in the fall. The young larvae of A. obliqua burrow 
gregariously, but the larvae of N. oblonga are solitary miners. The 
nature of their mines, too, is very different. A. obliqua advances down 
the channels of the leaf, leaving the longitudinal partitions of the leaf 
intact and-only destroying the cross partitions, while N. oblonga produces 
a sort of blotch mine by zigzageing back and forth in the leaf and destroying 
both the longitudinal and the transverse partitions. Both species feed 
mainly on the chlorophyll of the leaf. When ready for the first molt, 
A. obliqua sheds its skin at once, right in the mine, near the healthy, 
undisturbed, succulent tissue of the leaf; but N. oblonga, when ready 
for its first molt, first severs the connecting tissue of the leaf in order to 
