TypHa Insects: THEIR EcotocicaL RELATIONSHIPS 503 
Sturmia nigrita Town. 
Sturmia nigrita Town. is a parasite which was found living in the larva 
of Arzama obliqua Walk. In each of the two instances observed, there 
was only one parasitic larva present in each of the larvae of Arzama 
obliqua. Both dipterous larvae emerged from their host on March 25, 
1918, through an opening which was made on the ventral side of the 
first thoracic segment. They pupated on the following day, and one adult 
emerged on April 9 and the other on April 10. 
RESUME 
From an ecological point of view, the insect inhabitants of Typha may 
best be considered with respect to the part of the plant they affect. 
Accordingly they are thus classified in the following pages. 
INSECT INHABITANTS OF THE HEAD OF TYPHA 
The insects inhabiting the head of Typha include, among the 
Lepidoptera, Lymnaecia phragmitella Staint., Dicymolonia julianalis 
Walk., Archips obsoletana Walk.; and among the Hemiptera, Jschnor- 
rhynchus resedae Panz. 
The work of L. phragmitella and D. julianalis is very similar. Each 
has one generation a year. Their early larval habits are almost identical. 
They feed first on the tender styles of the pistillate flowers of the cat-tail 
plant, leaving the stigmas to form a covering over themselves. Later, 
they advance deeper into the head and feed on the seeds and other parts 
of the fruiting spike. Both overwinter in the half-grown larval stage. 
In the spring before pupation, however, their habits become somewhat 
different. Many of the larvae of D. julianalis bore into the rachis of the 
head, where they transform. The majority of the larvae of L. phragmitella, 
on the contrary, remain in the pappus of the cat-tail, where they pupate 
in closely woven cocoons. A few of the L. phragmitella larvae migrate 
down to the stalk of the plant, where they bore into the stems and transform. 
The adults of both species emerge at about the same time. — 
L. phragmitella is a species of world-wide distribution, while D. julianalis 
is generally restricted to the Southern States, though it is found as far 
north as New York. Of L. phragmitella the writer has found as many 
as 76 pupae in asingle head, while of D. julianalis he has never observed 
more than six or eight individuals in one head. 
