PESTS AND DISEASES

Evening Post, Volume CXV, Issue 81, 6 April 1933, Page 19

PESTS AND DISEASES

COMMON TREATMENT

The present season, with, continued warm, humid weather, has proved a particularly trying one for gardeners. Plants have been particularly liable to mildew and other fungoid diseases while pests in the form of aphis, grubs, caterpillars, etc., have been more than usually, numerous. Much, extra labour is occasioned in combating these troubles unless spraying is done regularly as, left to themselves, the pests soon take control of the garden and, in many cases, entirely ruin the various plants or crops. For fungoid diseases the most common sprays arc either bordeaux mixture or lime sulphur, while for the various aphies black leaf 40 is perhaps the most, effective. Grubs and caterpillars are checked by applications of arsenate of lead. Every effort should be made to keep the ground clean by frequent cultivation as many —probably most— pests, whether fungoid or insect, breed in the ground. Too often rubbish is left lying- about instead of being destroyed or buried. Such accumulations are ideal harbours and breeding places for all sorts of pests and diseases.. Much of the green rubbish from a garden is valuable .for. digging in to form humus when it decays,'but where" this cannot be done at onco it is preferable to burn it rather than have it lying about. If it is desired to rot material down to form compost, a liberal sprinkling of limo over each layer of rubbish will largely help to purify the material and check .disease. . EARWIGS. These insects have been very numerous this season, some localities being affected worse than others. The general appearance of this insect is fairly well known, but it may bo news to some readers to learn that this insect is furnished with two very large and elaborate wings. If an: earwig is' examined, it; will be seen to bear at the hinder end. of the middle part, or 'thorax, a pair of short horny growths; ' These are • the', wing cases and beneath theni, beautifully folded, are the broad,' semi-circular wings. Strangely enough, • despite; the possession of these, earwigs seldom fly, and even when thrown into the air will not always spread, their wings. The suggestion has often been made that the insect confines its'aerial excursions to the hours of darkness, but there is very little evidence to support this belief; Another point- which has often been disputed is what use is mader of the nippers borne at the. tail end of the body. If the wings are unfolded artificially the pincers are. used .to refold arid replace them beneath the wingcases, but' it seems highly improbable that such formidable weapons have been provided "especially for this purpose. Earwigs have also been observed to capture', small insects by means of their nippers, but this !is by no means a common occurrence. The female lays a number of spherical eggs in the autumn or early spring, and these she guards from harm with as-much apparent solicitude and. affection as a. hen displays towards her chicks. When hatched, the young remain with the mother for some time, but the latter usually dies before her offspring .are fully grown. APHIDES. There are many branches of the aphis family, the two best known being the ordinary green fly, which is so troublesome on roses and other plants, and the black fly, which attacks broad beans, chrysanthemums, etc. There arc many peculiarities about the great aphis family. For one thing, although weak in themselves, a prey to many other insects, destroyed by the million in every summer shower, they are yet the gardener's worst foe, because of their vast numbers. Certain females lay eggs whilst others bring forth live young, but whatever the breeding method followed, certain it is that they reproduce themselves at such an nmazing rate that, were it not for the destruction of incalculable numbers by natural means, human life would be rendered impossible, for the insects would encumber the land to a depth of several feet in a single year. That this is no exaggeration will be readily conceded when it is mentioned that some varieties of aphis, notably the common green fly, grow to double their size in a day, commence to bring forth their own young when only five days old, producing from ton to fifteen new insects daily. One authority calculates that a single green fly might bo responsible for six thousand million descendants in the course of a year if left to itself.