Fig. 2. Large terminal gall and three smaller galls. 
later dark purple. The adult fly is shining 
black with simple, fragile wings. 
In the laboratory some flies emerged in 
autumn, probably in response to the high indoor 
temperatures. 
When young larvae were removed from galls 
and placed on the soft tips of new shoots in the 
laboratory, they made no attempt to enter the 
new host plant. (In other experiments by the 
author with the gall moth Morova subfasciata 
Walk., the larval insect was capable of re-enter- 
ing new shoots of the host after removal from 
the galls.) The attempt to elicit new galls on 
Myrsine australis with living larvae of the 
midge was unsuccessful, therefore. 
It is readily apparent that each gall is com- 
posed of two or three modified leaves which 
are fused together. 
A trace of the leaf blades may be seen at the 
top of the gall. Evidently the gall is derived 
chiefly from swollen petioles, which are curved 
and fused together to form a small urnlike 
structure occupied by one or more larvae. 
There is some variation in the degree of 
fusion of the modified leaves which form the 
PACIFIC SCIENCE, Vol. XXI, January 1967 
walls of the gall. Where the leaf margins are 
merely closely pressed together, a boundary is 
recognizable ; in other cases the cells of each 
contributing swollen leaf are completely inter- 
knit, leaving no demarcation. 
Some galls are partitioned into two compart- 
ments, and others contain only a single loculus. 
The number of larvae per gall ranges from one 
to four, the larger galls generally containing 
more larvae than the smaller ones. 
In living galls the vaselike cavity is lined by 
nutritive tissue which may bear finger-like cells 
Fig. 3. Longitudinal section through a large gall. 
cn, Chlorophyllous nutritive parenchyma; m, midge 
larva. 
