ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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(Coccidotrophus socialis) which excavate the loose pith or clean things up 
if there have been previous tenants. The females lay eggs ; the larvae 
and adults feed on the growing parenchyma. But the beetles bring in 
female mealy-bugs ( Pseudococcus bromelise ), which suck the plant juices ; 
and both larval and adult beetles massage the bugs for the sake of drops 
of honey-dew. There is an intimate biocoenose. The collaboration 
may be disturbed by the thief-ants ( Solenopsis altinodis ) and other 
intruders. When the young tree ceases to be a shade plant, ants {Azteca 
and Pseudomyrma ) take up their abode in the petiole, also keeping- 
partner Coccids, and the beetles are only found on the young trees. 
There is another beetle, Eunausebius, which behaves in the same way as 
Coccidotrophus , but it is much less vigorous and seems like a feeble, 
anmmic, and harried species. An account is given of other “ social ” 
beetles, and the significance of the remarkable co-operation is discussed 
in its ecological and psychological aspects. J. A. T. 
Tachigalia Ants. — W. M. Wheeler (. Zoologica , 1921, 3, 137-68). 
Two species of Pseudomyrma and two of Azteca are definitely attached 
to Tachigalia as host-tree. The recently fertilized queens of these ants 
perforate and enter the petioles of young Tachigalias, close the openings 
behind them, and produce their broods. All the petioles of the larger 
trees are invariably inhabited by a single flourishing colony of one 
species only. No sooner are the petioles opened by the young broods 
of workers than the Coccids ( Pseudococcus bromelise) enter or are carried 
in by the ants and attach themselves to the areas of nutritive paren- 
chyma within the petioles. They are cared for by the ants and 
“milked.” But there are many other ants on the Tachigalia- tree, and 
a descriptive list of twenty-eight is given. The thief-ants and the 
leaf -cutters militate against the biocoenose. J. A. T. 
Variation in Mealworm. — S. A. Arendsen Hein ( Journ . Genetics , 
1920, 10 , 227-64). In most populations of larvae bought in the trade, 
two colour-varieties are found — chestnut-brown (CB) and orange-red 
(OR), and occasionally a type with black abdomen (BA). The most 
frequent larval anomalies exhibit themselves as a development of the 
rudimentary wings, as a partial fusion of the segments, and as a 
variation in the number and position of the spines occurring on the 
last segment. The male and female pupae are easily distinguished. 
The sex ratio may be taken as equal. In the adults there are size 
differences, sex differences, differences in egg-production (359 the 
maximum obtained), in the duration of egg-production (normally two 
months). The female survives the male by about fifty-one days ; the 
male may mate with several females. The yellow and red colour of the 
eyes and some forms of reduction in the number of tarsal and antennal 
segments are based on hereditary factors. The yellow eye-colour has a 
sex-limited descent, but the red appears to be not sex-limited. J. A. T. 
Blue-green Caterpillars as a Mutation. — John H. Gerould 
{Journ. Exper. Zool., 1921, 34 , 335-416, 6 figs.). In a closely inbred 
stock of protectively-coloured grass-green caterpillars of Colias philodice 
there appeared numerous conspicuous blue-green forms. The three 
broods in which they first appeared showed the 3 : 1 ratio, grass-green 
