170 
THE ESSEX NATURALIST. 
leaves, and in maturity scale-like ad ressed leaves. So different 
are the two types that for a number of years the juvenile foliage 
was thought to belong to a different genus and was given the 
name of Retinospora ; cuttings taken from this stage never 
assume the mature type of foliage. 
The junipers form the last genus, Juniper us, we have to con¬ 
sider. The fleshy berry-like fruit is formed by the union of 
bracts, which are at first free. Our English Juniper, J. communis, 
is seldom grown, but the Chinese species, J. Chinensis, is often 
cultivated and forms a bush or small tree. Both the juvenile 
and adult types of foliage are seen on the same plant, the former 
towards the base where the light is dim, and the closer scale 
leaves at the ends of the shoots where exposed to strong light. 
The male plants are more compact and pyramidal than the female. 
I have attempted to give in this sketch merely the most strik¬ 
ing characters that distinguish the genera and species from each 
other. I have not touched on the subject of the more intimate 
structure of the leaves, the stem and the cones, all of which seem 
to call for attention. But should anyone feel drawn to making 
even a cursory study of conifers, I can assure them from my 
own experience that it is one of ever-increasing interest. 
ON INSECTS SUCKING THE SAP OF TREES. 
» 
By CHARLES NICHOLSON, F.E S. 
(Read 29 th November, 1919.) 
O N the occasion of the Club’s meeting on 30th Nov., 1918, 
when Mr. Miller Christy read some notes on the above 
subject—subsequently printed in this volume (pp. 10-12)—I 
expressed a wish to inspect the tree to which his notes referred, 
and, at his invitation, I paid a visit to his garden at Chignal 
St. James, on the 23rd August, 1919. 
The day was dull and not over warm, but occasionally bright¬ 
ened with short bursts of sunshine. On arriving at the tree 
in the afternoon, I found a good number of wasps scattered up 
and down the main trunk of the tree, from near the ground to 
a height of at least 50 or 60 ft., and also along a long limb, which 
extended almost horizontally towards the S.E. Most of the 
wasps (all of which appeared to be workers of Vespa germanica), 
