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Introduction.

There is an increased and increasing risk of loss and destruction from injurious insects to many of the cultivated crops of this country.

Thus, corn of all kinds, fruit trees, hop plants, clover, turnips, and mangel wurzel are continually attacked by insects, both of kinds well known and long known, as well as of kinds that are new, or whose ravages have only been recently noted, and which in certain cases, as the mangel wurzel fly, Anthomyia Betæ, seem to have been imported with the plant. The mischief caused by this fly has become greatly intensified even within the last five years. Curtis, writing of it in 1859, thought that its injuries would not be of much consequence. Again, the "turnip fly" or "flea," Phyllotreta nemorum, has enormously multiplied with the extension of turnip culture, and in some seasons has caused very heavy losses to farmers. Originally feeding upon charlock and other cruciferous plants, it leaves these now for more grateful food, and breeds rapidly in these favourable circumstances.

Naturally this increase of insects follows pari passu the extension of culture and the distribution of the plants which are the special subjects of their attacks. But it is found that in the case of wheat, and clover, and other crops, which have been cultivated in due rotation in the same fields new injuries from insects have been noticed. It must be remembered, however, that the number of observers among agriculturists has increased of late, and the manner of observation has been changed and page 6 improved. It is of course quite possible that the supposed new insects may have been working unnoticed for generations.

Admitting to an extent the advance of intelligent observation and the spread of entomological knowledge, it is quite clear that not only is the destruction occasioned by insects larger than ever it was, but that there are insects at work in the fields which were not there in the times of our forefathers. One reason for the progressive increase of insects is that a larger supply of food encourages the proportional propagation of insects fond of and living upon it. Another undoubtedly his that the systems of land treatment have completely changed, and become more artificial, by which the balances of nature, "the aggregate action and" product of many natural laws," as Darwin has it, have been disturbed.

Insectivorous insects, for example, may have been diminished by changed methods of management. High and altered farming may have made certain crops more delicate and liable to insect attack. The slaughter of insectivorous birds and animals is most wholesale and indiscriminate. The hand of every one, to take an instance, is against moles, and yet farmers wonder that wireworms become more abundant each succeeding season.

With regard to new insects there are continuous opportunities for their introduction into England in all kinds of agricultural produce from all kinds of climates and soils. Insects are probably imported into as they are exported out of England. Fortunately the climate of this country does not suit the habits of most foreign insects. The dreaded potato bug, Doryphora decemlineata, would have without any doubt gained a settlement here if the conditions had been suitable. But on the other hand it is tolerably certain that the hop aphis was taken to America in hop roots or sets sent from England. Until 25 years ago, Professor Lintner states, this insect was unknown in the American hop plantations, and now it is becoming a serious trouble. Several other insects destructive to corn, hop, and fruit crops have been brought into America from Europe with seeds, plants, and fruits, and are threatening to become more troublesome in this "home of insects," as America has been called by entomologists, than they ever were in their native land. America has retaliated by exporting the Phylloxera into the French vineyards, to the utter confusion and indescribable loss of the wine producers. Within the last few years scale insects have appeared in the Californian orange groves from Australia, and orange, citron, and lemon growers in other parts of the world have lately been exercised in their minds by the appearance of pests of this species.

Seeing then these dangers from the spread of indigenous insects, and the fear of the introduction of new species from page 7 foreign countries, it is most desirable to diffuse entomological information as to the habits and life-history of injurious insects in a simple and intelligible form, for the use of farmers, fruit-growers, market gardeners, and all who cultivate the land, and at the same time to give practical modes of prevention, and remedies against their attacks.

The hop plant in particular has many insect enemies. Some of these are most dangerous and destructive, and if not prevented or checked will soon ruin the crop. It appears as if the liability of hop plants to be attacked by insects has considerably increased during the past 30 years, and it is believed by hop planters that some of the insects which now vex them were not known in the hop plantations until recently. As the planters are anxious to learn what has been ascertained regarding the insects affecting hop plants, it is considered desirable to publish this record of 10 species of insects more or less injurious to them, giving descriptions of each insect, together with its life history, its modes of attack and the results of its injuries, also an account in some detail of methods of prevention, and of measures which have been found efficacious in stopping or alleviating injuries.