The South Australian Naturalist. 
lines of overlying objects are fairly delineated by the unoccupied 
spaces. A count showed that more than 300 eggs were attached 
to a flat, circular pebble scarcely one inch in diameter. 
It has been mentioned that backs wimmers (Anisops hyperion 
and A. doris) were also greatly in evidence in the reservoir. Mr. 
Shepherd notes that this is the first time in years that he has 
seen this water practically denuded of its usually plentiful supply 
of water-fleas and mosquito larvae; this is without doubt due 
to the depredations of the abundant backswimmers. The eggs 
of Anisops have been previously described and they may be dis- 
tinguished at a glance from those of Porocorixa (S). Curiously 
enough, no Anisops ova were found amongst the Broken Hill 
material. Thinking it certain that the myriads of bugs would 
migrate towards winter, the writer asked Mr. Shepherd to look 
out for any such occurence. In May one of a party of sports- 
men who often spend a night in covert near Stephens Creek 
brought some Anisops to Mr. Shepherd, asking what they were 
and describing the circumstances in which they were taken. He 
stated that on several recent occasions, when lying on the banks 
early in the morning (after a night of duck shooting), his party 
observed ‘‘millions of these white bugs suddenly rise out of the 
lake , ascend to a fair height in a spiral cloud, and then make off 
at a good speed, as a rule with the wind; numbers fell back, and 
during a flight were crawling all over us.” 
On June 2Sth the water in the reservoir was rapidly lowering. 
By this time almost all of the bugs, both backswimmers and boat- 
men, had disappeared. 
One evening in January, 1923, the writer carefully searched 
a pool in a claypan at the Myponga swamps, South Australia, and 
found a few backswimmers only. Early next morning, however, 
the muddy water was crowded with a species of water-boatman 
(Porocorixa parvipunctata) . These bugs evidently flew to the 
pool during the night; this was at a time of full moon. 
Migrations of acquatic bugs have not been previously noted 
in Australia, but such occurences have been described in other 
countries. 
REFERENCES. 
1. Kirkaldy, G. W., Entomologists’ Monthly Magazine, XXXV., 
o P* ^outh Australian Naturalist, ii. (3), p. 55). 
2. Kirkaldy, G. W., loc. cit., xxxiv., 1898, p. 173, and Revue d. 
Entomologie, xviii., 1899, p. 95, fig. 6. 
^11^' fP’ W ^outh Australian Museum, ii., 1922, p. 
4. Hungerford, H. B., Bulletin Brooklyn Entomological Society 
. Hale, H. M., loc. at., li., 1923, p. 410, pi. x,, fig. 4-5, 
