THE HISTORY OF THE CODLIN MOTH AND ITS BEARING ON THE MOTH ACT.

New Zealand Herald, Volume XXV, Issue 9075, 8 June 1888, Page 3

THE HISTORY OF THE CODLIN MOTH AND ITS BEARING ON THE MOTH ACT.

The Rev. A. M. McCallum has sent us the following, which will be read with interest by fruitgrowers and others concerned : — The little insect known by the name of the codlin moth has suddenly been invested, by Act of Parliament, with importance and interest to every owner of an apple tree or two, and even to every one who likes nice fruit, and is still partial to the nursery drama, " A Was an Apple-pie." A little common knowledge of entomology, so far as this very destructive creature is concerned, may prove useful just now to all such people, as well as to incipient legislators and prospective fruitgrowers, and not least to a few humble fruitsellers and poor country settlers throughout the land. These moths pass the winter in the pupa state in cocoons under the loose bark of the trees, or in such crevices as they may find in buildings, bins, or fruit boxes, or even in dwelling houses. In this state they are, of course, dormant and harmless. About the time when the apple - blossom begins to open they appear as moths, the time varying in different parts of the country and in different years. As soon as the apple, quince, or pear is out of blossom the moth begins to deposib its eggs in the calyx or blossom end, usually one at a time, and one to each apple. This is believed to be almost always dono in the night. The moth itself being small, ana of a brownish colour, is seldom seen. In about a week these eggs produce a very small whitish worm, with a black head, which eats its way gradually into the core of the fruit. As a rule, the apples containing worms can be distinguished by a peculiar reddish-brown tuft of dust, the castings of the worm, adhering to the calyx. But owing to the worm being in an early stage of existence, or accident having removed this patent sign of its presence, it is often very difficult, or almost impossible, to say that the fruit is at all infected. It may be only after a time, when the fruit is in transit on shipboard, or in the store of the fruiterer, that the presence of the worm is detected. Very many, but not nearly all, of the wormy apples fall, some before and some after the larva: have matured and passed out. They usually make their exit through the sido, making a much larger hole for this purpose than the one by which they entered ; but sometimes they escape by the calyx or flower end, by the same perforation by which they entered. It is a curious fact in the natural history of these insects that the larva finishes off by feasting on the pips, containing as they do prussic acid, which, so far from being hurtful to their constitution, seems to aflord some element essential to their spinning operations afterwards, or development otherwise in all the attire of the full-blown moth.

I give from the best authority at hand the life periods of this terrible insect as follows : Egg state, one week ; larva state, four weeks ; pupa state, two weeks ; imago or moth state, one week; in all, eight, weeks. Favourable or unfavourable circumstances, such as temperature, may lengthen or shorten these poriods. It is now known that in the North Island, and in .ill corresponding latitudes, there is a second brood which is ready for another raid, when the mild weather of spring or autumn brings them out. I believe many of this brood pierce the apple, sometimes very slightly, without injuring it much, through the rind ; and it is certain that many individuals of this lot leave the apples, after they have been gathered, apparently sound, and secrete themselves not only in the crevices of the cases containing the worm-eaten fruit, but also in boxes, which may bo at hand, containing fruit quit© free from infection, and in cases containing machinery or other goods, and in crevices of timber which had been placed adjacent to infected fruit on board of ship. The number of eggs which each female moth will deposit, in as many apples, has been variously stated by those who have made the ravages of the codlin moth a subjcct of investigation. It is believed that each female moth will produce from 50 to 60. It may bo thrice that number. It will readily be seen that with two broods in a season, even one of those moths may commit a great deal of havoc in an orchard before the season closes, and that it is the interest of everyone who owns fruit trees to use'the utmost care to destroy them, or prevent their presence by fumigation or otherwise as much as possible. Although it is absolutely impossible to stamp out the moth completely, when it has once entered the country, by legislative enactments, still very much can be done by orchardists themselves to lessen the evil. An eminent entomologist enumerates four methods of destroying the moth, each more or less successful. These are : destroying insects in their winter quarters; picking the wormy apples from the trees ; gathering the wormy fruit from the ground, or letting swine and sheep have the run of the orchard ; entrapping the worms in bands and other contrivances.

Now, with regard to the Act now before the Legislature, a careful study of the natural history of the moth and the practical operation of the proposed law will show us that it is an ill-considered and impracticable enactment, and would fail of the desired object, while it) would be vexatious and costly in its application. A few of the difficulties likely to arise from this point of view may be briefly mentioned :— 1. The Act does not provide for preventing the insect being continually introduced in fruit imported from abroad, and distributed in country districts with imported machinery, onions, palings, etc. 2. The Act devises no means by which the moth can be destroyed or their number abated, while no law of man can hinder the nocturnal tight of the moth. The law compelling the owner of every tree affected by its visits to apply a wash to the whole tree as often as is required, with an expensive and very dangerous compound, is a law that can neither be tolerated, carried out, nor enforced. " Paris-green " is a worse blood-poison than the arsenic or copper of which ib is a chemical combination. It cannob bo used with safety if there is any chap, cut, or abrasion of the hands of the person using it. .It is dangerous to have about where there are children, and its apElication requires skill. Many people aving a few trees would require the services of a professional workman, at more cost than all the fruit saved might bo worth. The operator might not be available at the right time when his services would be of use. Besides, the proper time varies with the blossoming of the trees. Some trees blossom one half one day and the other half another. In an ordinary orchard the period in which trees are in the stage to make the application extends over a considerable time. This means great expense and hardship, at a time when orchardists and farmers must attend to other matters. Bandaging trees under arbitrary directions, and having these bandages regularly examined, would prove a most costly and irritating matter to many a fruit-grower. In fact no would rather destroy his trees altogether than submit to such orders by Government agents, and pay the cruel and rul.ious penalties which an inspector or local Board would eagerly enforce, with costs to boot.

3. The last objection is worse than the first. From the habits of the moth it will be seen that its presence cannot always be observed when the fruit is gathered or sold. By-and-by it makes its appearance, and the unfortunate grower, and some poor widow, perhaps, who has tried to find bread for a family by growing or selling a little fruit, is pounced upon, aj)d mercilessly fined in a penalty of £5 or £10. The tiling is monstrous, and I cannot but wonder that good and sensible men would let their hobbies or personal interests carry them so far. Add to this that no one is allowed to sell or buy fruit only slightly affected, though it be quite wholesome, and the only sort many persons can afford to buy. This will be a serious loss to many who have had but poor returns for their labours, still more curtailed by foreign supplies, which do not cheapen fruit to tne community, but to this loss fruit-growers would cheerfully submit if the remedy were limited to this, and restriction on importation, which would speedily make home supplies abundant.