22 
THE WEEKLY ENTOMOLOGIST. 
LAEV AE. 
During tlie Interregnum between 
the ‘Intelligencer’ and the ‘Entomol- 
ogist’ several interesting facts have 
been brought prominently forward 
with respect to the management of 
larvae and pupae. It may, perhaps, 
be interesting to your readers, and 
advantageous to the race of larvae if I 
briefly allude to them. 
It was stated at one of the meetings 
of the Northern Entomological Society 
that if a little sugar be dissolved in 
the water, used to keep fresh the food 
of caterpillars the result will be seen 
in the increased size and healthiness of 
the feeders. If true this is a singular 
fact. Can it be so ? 
Some important observations have 
been made on the diseases of larvae. 
It has long been known that if fed 
on the young juicy leaves growing at 
the end of the twigs of their food- 
plants they are generally afflicted with 
diarrhoea, and it is not surprising that 
larvae forced, when half grown, to 
change their kind of food [as from oak 
to elm] should be injured_by the new 
diet, but it is certainly singular that 
their health should be affected by 
their food being gathered from a tree 
to which they were not accustomed, 
although of precisely the same 
species. Yet it is positively asserted 
that even this is likely to produce 
disease. 
These facts would tend to show that 
much hitherto accounted inexplicable 
in the economy of larva), and simply 
produced by a combination of acci- 
dental circumstances, is really pro- 
duced by the most fixed and invariable 
rules. How many of the cases of 
extraordinary mortality among them, 
may have been caused by an unfor- 
tunate supply of food, gathered from 
an unaccustomed tree ! And if these 
two statements can both be established 
by facts, how great a benefit have the 
gentleman who have made them be- 
stowed on the Entomological public! 
The latter of the two facts can only 
have been arrived at, as the result of 
very careful and exact observation, — 
and may fairly be regarded as an in- 
stance of the reward that is sure to 
follow such painstaking study. 
The former fact is doubtless the 
most astonishing, as it teaches us that 
in order to bring insect life to perfec- 
tion, somthing is wanted beyond the 
ordinary resources of nature, while 
the latter is, in no way surprising, 
but simply indicative of tho labours 
of a careful naturalist. 
Does not the theory of the condi- 
ition of food when eaten by the larva, 
producing its effect in the perfect 
insect, border on the domain of 
Chemistry ? IIow far is it safe to 
apply this principle? What would 
be the effect of artificially preparing 
the food in other ways ? And would 
the result be confined to an increase 
or diminution of the size of tho insect 
so fed ? or would it extend to a vari- 
ation in form or in colour ? 
These are all questions that may 
fairly bo usked, but which can only 
bo satisfactorily answered by many 
and careful experiments. 
