A Hitherto Unrecorded Midge Gall of Myrsine australis (A, Rich.) Allan 
B. C. Arnold 1 
Stem galls on Myrsine australis were reported 
by Lamb (I960) in his checklist of New Zea- 
land Zoocecidea, but there appears to be no 
record yet of the conspicuous bud galls (Fig. 
1) found near the branch extremities of this 
handsome tree, which is readily recognized by 
its red, mottled leaves, red stems, and dark red 
bark (Allan, 1961). When cut open, the dark 
bud galls may be seen to contain small white 
midge larvae or pupae in various stages of 
metamorphosis. 
The present report is concerned chiefly with 
anatomical modifications of the leaf bud by the 
midge larvae. 
I am indebted to the University Grants Com- 
mittee for a grant in aid of the work. 
METHODS AND MATERIALS 
Galls of Myrsine australis were examined on 
trees in the forest over a period of 16 months, 
and specimens for histological examination 
were fixed in Formo-acetic-alcohol. Serial sec- 
tions were cut at 10^ and stained in Safranin 
and Fast Green (Johansen, 1940). Freehand 
sections of living galls were made to observe 
the details of nutritive tissue which is slightly 
distorted by the fixative. 
Pupae were removed from galls and left in 
small stoppered glass vials to transform into 
adult midges. 
Artificial formation of the galls was at- 
tempted by removing small larvae from galls 
and placing them on tender buds of stem cut- 
tings. The cuttings were kept under bell jars in 
the south light of the laboratory window, with 
the base of the cuttings immersed in tap water 
in small flasks. 
OBSERVATIONS 
New galls were first apparent in December 
as dull olive-green, budlike structures (Fig. 1). 
1 Department of Botany, University of Canterbury, 
Christchurch, New Zealand. Manuscript received Au- 
gust 31, 1965. 
Fig. 1. Bud galls of Myrsine australis. 
Within two months they had become almost 
black outwardly, masking the chlorophyll and 
red pigmentation of the internal tissues. Dur- 
ing a mild spell of weather in winter, a few 
additional young galls were formed in June, 
but this would seem to be an exceptional event. 
Under natural conditions in the forest, galls 
appear to live 10-12 months. By the following 
spring most galls are shrivelled and dry. 
Mature galls range from I/4 to % inch in 
length. Frequently the terminal gall of a branch- 
let may dominate the subjacent lateral galls 
(Fig. 2). 
The midge larvae are small and white with 
prominent salivary glands containing polytene 
banded chromosomes. The larvae transform 
within the gall into small black pupae with 
prominent eyes which are crimson at first and 
115 
