THE CODLIN MOTH.

Otago Witness, Issue 2490, 4 December 1901, Page 10

THE CODLIN MOTH.

• Knowing that the season has arrived when, <. without de}ay, prompt measures require to be at once put intQ. force by every grower oi apples for the control of this destructive pest, the proprietors of this journal have, i with the view of disseminating reliable information on the subject, obtained particulars from Mr J. C. Blackmore, who has devoted much time in connection with other workers, to the study of its life history ana methods for its suppression. His reply t > our inquiries, we feel sure, will be read with interest by every fruitgrower, as it contains several material points with reference to the life history of the moth not generally understood. He remarks : — Wherever apples are grown on a commercial scale, the codlin moth soon becomes a serious problem. The ease with which the insect introduces itself and the difficulty, not to say impossibility, of finding any complete remedy for its depredations make ifc easily the chief of the apple-grower's i trouble^. Recognising the importance oi j this problem, and the need of its solution, ! and with a view to ascertain any fresti j facts of importance, close observation has re- | cently been made by several investigators to determine the manner of life and behaviour, both in confinement and in the orI chard, of this enemy. The questions prn- ! pounded were: First, when is the egg laid? .Second, where is it laid? Third, how long after the blossoms fall before the larvae begin to efit? Fourth, how do they begin eating? Fifth, what proportion enter at thej calyx? j Gathering together, and summarising as , briefly as possible, the results of various investigations, and comparing thr same with observations during the past two years made by the writer, the life history of the codlin moth is something as follows: The number of broods and its exact time of hatching out during early sau'ius; is somewhat ua-

certain, depending on climatic conditions In warm climptcs, iho firf-i moih«, which emerge early in t: c spring, may pass thiough four generation, in a season; thelaggaids qct through but h\o; the majority, three. In cold climate" not a large per c'jnc. develop even a second brood.

The Gist of It.

The moth emerges about a week after the blossom has fallen from the apple trees, and some of them, the laggards, considerably later. They deposit their eggs on the young apples, as well as scatter them profusely about on the foliage, especially on leaves of a cluster on which there is an apple. Eight to ten days later, in ?ome instances in less time, depending on the weather, the egg hatches, and the young larvae seek for a hiding place. A considerable percentage enter within the calyx cup; a few eat a little of the leaf before doing this; some where there are points of contact, such as two apples being elo°e together, or a leaf touching an apple. It lives in the apple some 10 to H days, leave? it, finds a hiding place, spins its cocoon, and often changes to a pupa, and comes forth as a moth about a month after the egg" was laid. In this respect it is irregular as regard? time. In confinement it is common for tl-c larvae to change to pupae within the apple, and one close and reliable observer expresses the opinion that the majority of early brooos thus transform. The last brood in autumn does not pass into the chrysalis state till nearly the time that apples filossom the following spring, but remains in a quiescent condition in the cocoons. The egg of the codlin moth is about the size •of a pin's head, and looks not unlike a «nall drop of milk ; and in badly-infested orchards the eggs are easy to detect, and more prevalent than is generally supposed.

Suggestions for Treatment,

The following suggestions as regards the most encouraging line of warfare to follow, and which have given best lesults, are: First, spray with Peris green, or arsenite of lead, as generally recommended, observing when using the Paris green to add the lime to prevent burning of the foliage. Apply the first spray about one week after the blossom falls, or in time to get the calyx cups well filled with the poison before the calyx lobes turn down, so that they may close over and hold it there ; second, spray about two weeks after the first with Paiis green and Bordeaux mixture, or with kerosene emulsion (strength, one part of the standard mixture diluted with 20 of water) ; or, better still, observe carefully, and apply this when the eggs are being laid in abundance on the leaves. For later sprayings, both laboratory as well as field experiments indicate that kerosene emulsion is more effective in destroying the eggs on the leaves than either Paris green or Bordeaux mixtuie; in fact, for the purpose of destroying the eggs its use has given most excellent results. As a further precaution, gather infested fruit and destroy the grub within before it can escape ; keep the trees smooth by scraping off all rough bark, and place bands around the trunk within four weeks after the blossom falls; remove often the bands, kill the larvae and replace. Place screens over the doors and windows where fruit is stored, examine the storerooms early in spring for hibernating worms, and eradicate by fumigation or other effectual method. The policy outlined here will, as elsewhere tried, result in saving the greater proportion of your crop. If you don't believe this, observe for yourself, and endeavour to find out more practical methods. — Motueka Press.