524 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
L December 6, 1888, 
known. It eclipses all others in size, substance, and colour. At present 
the stock is limited, hardly reaching half a dozen plants. Then when 
the visitor has had his fill of specimens of foliage and flowering plants, 
he will find abundant amusement, accompanied by a good deal of 
instruction if he will, by inspecting the Lfelias, Cattleyas, Dendrobes, 
Oncidiums, Odontoglossums, Masdevallias, Lycastes, Cypripediums, and 
such like, which merit greater detail concerning them, but time and 
space forbid.—J. H. E. 
ECONOMIC ENTOMOLOGY. 
[Presidential address to the Highbury Micioscopical Society, by James A. Forster.] 
{Continued from giage 455.') 
An important element in the education of a farmer should be the 
'teaching the. use of the magnifying lens and the naturalist’s habit of 
close and minute examination and accurate estimation of the facts he 
observes. Indeed, not only for the farmer is this teaching necessary, 
but I would urge that it, with a general teaching of zoology, ought to 
form a distinctive part of every boy’s education. I mean that Natural 
History should not (as is now mostly the case where it is taught at all) 
be taught as an extra subject, but it should have a prominent place in 
the curriculum of every school, to be taught with as much regularity 
and earnestness as grammar or language. These, surely, cannot °excel it 
as a means whereby to train the youthful intellect to habits of close, 
careful, and accurate reasoning, order, and patient attention. The 
study, properly directed, of God’s creatures can hardly be of less value 
as a mental and moral training than that of a dead language, and must 
necessarily bear much more nearly on our daily life. = ° 
The insect kingdom—by far the most numerous in species of any 
■corresponding group throughout animal life—is, as you are aware, 
classified into some twelve or thirteen principal families. Each of these 
families sends its (]uota to the host of the insect marauders of our 
gardens and fields. Happily for us, each group also contains not only 
■species, but entire families, whose object in life is to prey upon these 
pests, to hunt them down, to devour them in each stage of their life. 
Thus has Nature put a check upon their increase, without which the 
human race would quickly have been eaten out of the land, Without 
"these natural allies, we should have been powerless to overcome these 
deadly if minute enemies—the more deadly, indeed, because of their 
minute size, which renders it so difficult for us to discover them till the 
mischief they cause is well-nigh irremediable. 
It is, then, evidently of the first importance that we should acquire 
that knowledge which shall enable us to recognise our friends so as not 
to confound them in the wholesale destruction we attempt to bring 
about of our pests. As a first step towards this knowledge, it is to be 
observed that the Iusecta—like the higher animal kingdoms—comprises 
groups of vegetable-feeders and of flesh-feeders. Now, it is amongst the 
former that are found those insects that cause the most serious losses 
to our various crops ; while it is to the latter—to the predaceous and 
carnivorous class—that we are indebted for the keeping within bounds 
the enormous increase of the devourers of our fruit and food that would 
otherwise take place by reason of the wonderful powers possessed by 
them of reproduction. It is thus, as in so many instances throughout 
life, that Nature provides, as it were, a natural balance of forces, and I 
would ask, \\ hat can we do more wisely than avail ourselves of 
Nature’s own means of keeping in check the myriads of foes that would, 
if left to themselves, turn our fields and our gardens into barren wilder¬ 
nesses ? Had our Hop-growers perceived the truth of this, and persis¬ 
tently and patiently fostered by every means in their power the settle¬ 
ment in their gardens, and the increase, of aphis-eating insects, such as 
the Lady-birds (Coccinellidm), they would have largely mitigated, if not 
entirely prevented, the almost incalculable losses they have suffered 
from the so-called “ black blights,” which, instead, 'have become of 
increasing frequency during the past fifty years. The great loss caused 
by the ravages of aphides alone to Hop-planters and the whole com¬ 
munity may be well brought home to us by the following facts and 
figures :— 
_ In 1882 a serious blight occurred throughout the Hop-growing dis¬ 
tricts of England, causing a reduction of the average production from 
7 cwts. per acre to less than 1J cwt. Now, as in that year the Hop 
acreage was about 65,600 acres, the total yield of which was under 
115,000 cwts. instead of 460,000 cwts., it follows that the loss on the 
■crop was about 345,000 cwts., which, taken at the average price of Hops 
for the preceding twenty years (£7 7s. per cwt.), amounts to over 
£2,500,000 sterling loss in that year to the cultivators alone. But it 
-was not they alone who directly suffered for it. It is estimated that 
not more than £150,000 was paid that season for the picking of the 
■crop, while had it been an average one, the cost of picking would have 
amounted to nearly £400,000. So nearly a quarter of a million sterling 
was lost to the labourers in that one season. What an amount of 
misery is expressed in these figures 1 
A few facts concerning our Apple orchards may further serve to 
justify my claim for the economic importance of my subject. There 
are in England, according to recent agricultural statistics, at least 
250,000 acres under fruit cultivation, of which by far the larger part is 
•occupied by Apple orchards, forming a very important item in the crops 
of many districts in Devon, Somerset, Herefordshire, and Kent. Now, 
the Apple, amongst its many enemies, suffers from the attacks of two 
little moths and their caterpillars—the small Ermine moth (Hypono- 
meuta padella) and the Codlin moth (Corpocapsa ponomella). The 
former, in the years 1865 and 1887, entirely devastated whole orchards 
throughout Kent and also the West of England. Hundreds of acres of 
orchards were to be seen in the month of July of those years without a 
leaf upon them—as bare, in fact, as though in midwinter. Every leaf, 
every bud, every blossom, had been cleared off by innumerable swarms 
of Ermine moth caterpillars, which had not only entirely destroyed the 
crop for the season, but had so seriously injured and weakened the 
trees that they produced but very small and poor crops in subsequent 
seasons. Again, in 1880, much damage was done by the same insect. 
In 1877, the second of the above-named moths, the Codlin moth, 
caused much mischief to the orchards of Kent, where, it was estimated, 
about thirty per cent, of the Apples fell immature by reason of the 
maggot having penetrated to the core. And, further, it was found that 
a large portion of the fruit that did ripen would not keep from the same 
cause. As this moth specially attacks Pippins and the choicest descrip¬ 
tions of dessert Apples, the pecuniary loss to the growers must have 
been very large ; but as there are no official statistics it is not possible 
to estimate the amount. In the cider-producing districts, the destruc¬ 
tion of half the crop, which frequently takes place through the ravages 
of these two insects, must represent a very heavy loss to the farmers. 
Very frequently the above mischief is attributed to the weather, to the 
east wind, to that all-embracing word when used by the gardener, 
“ Blight; ” but if the observers would look closer and more accurately 
the true enemy might easily be discovered. When a gardener, seeing 
one of his trees with all the leaves shrivelled up, drawn together, and 
enveloped, as it were, in cobweb, with the blossoms falling off before 
mature or not opening at all, tells you in a mysterious manner that 
there is a “ blight in the air ” or that the tree is “ struck,” he is only 
confessing his ignorance and want of observation, and consequent 
inability of taking such precautions as shall render a recurrence of the 
misfortune unlikely or at any rate less severe. 
The limits of this paper and my lack of knowledge alike render it 
impossible for me to attempt more than to describe a very few of our 
insect foes ; but these that I shall now mention will serve as a sample 
of the rest, and the consideration of their life-histories will, to some 
extent, indicate the methods of observation necessary for their study. 
As I have already said, each of the great insect families contributes its 
quota to the devastating army. Certain families—notably, the beetles 
(Coleoptera), the bees, wasps, ants, &c. (Hymenoptera), the ephemeras, 
dragon-flies, &c. (Neuroptera)—send us friends as well as foes ; others, 
like the aphides (Homoptera) are unmixed evils. The aphides, are 
perhaps, the most terrible and dangerous of all our scourges, and one of 
the most difficult to overcome, their amazing power of increase being 
unequalled throughout the animal kingdom. There is scarcely a plant 
that is not attacked by them, nor a locality where they are not to be 
found in numbers, and, under their popular name of “ blight,” dreaded 
by all gardeners and cultivators. At first sight it would hardly seem 
that they could be worthy of much attention. Their round, short 
bodies, nearly all belly, are carried on the frailest of legs ; their habits 
are so sedentary that they seem intended to remain stationary ; where 
they are born, for the most part, there they live and die, without giving 
any evidence of the instinct so frequently met with in insects. Their 
lives might almost be described as vegetable. Yet their organisation is 
most singular, and their fecundity in certain seasons so prodigious as to 
make them a real scourge. They infest every kind of tree, plant, or 
flower. The rarest flowers in our hothouses and the commonest flowers 
of the hedgerows alike serve them for home and food ; in short, they are 
of all climates and all seasons. 
They are both oviparous and viviparous. Their eggs, fixed to the 
plants by a viscid secretion, have the appearance of little, black, oval, 
shiny grains, deposited irregularly in large numbers on the sheltered 
side of branch or leaf. The young larva when extruded from the egg 
is nearly of its full size, and presents but little difference in appearance 
to the perfect insect. It emerges from the egg by a sort of trap or 
cover, and falls out backwards. Shortly after their birth, the young 
aphides work their way on to the tenderest and greenest part of the 
plant on which they find themselves. They crowd close together, their 
heads usually pointing to a common centre, and fix themselves by means 
of the large beak with which their mouth is furnished, and through 
which they incessantly suck up the sap of the plant, exhausting it and 
causing strange excrescences like galls, and in the end the plant becomes 
deformed and ruined. When three days old, the larva changes its skin ; 
this is repeated three times at similar intervals. For the greater 
number, these metamorphoses produce but little change in appearance 
beyond a small tail, which develops at the end of the abdomen. When 
about nine days old, the female aphis (conditions of food and tempera¬ 
ture being favourable) begin propagating their species by giving birth 
to living larvae without having had any connection with the male. This 
has been described by Professor Owen as follows— 
“This larva, if circumstances of food and warmth be favourable, will 
produce a brood—indeed, a succession of broods of larvae—like itself 
without connection with the male. In fact, no winged males will have 
appeared. If the virgin progeny be also kept from any access to the 
male, each will again produce a brood of the same number of aphides, 
and carefully prosecuted experiments have shown that this procreation 
from a virgin mother will continue to the eleventh generation before 
the spermatic virtue of the ancestral coitus has been exhausted.” 
In favourable seasons, a certain portion of the third and fourth of 
these viviparous generations undergo special changes. At the first 
moulting small processes are observed on the back. These at successive 
moultings become largely developed, and after the fourth and last 
change of skin appear as large, fully formed, transparent wings, on 
