654 Journal of AgriculUire, Victoria. [11 Nov., 1918. 



CoDLiN OR Codling Moth (Cydia (Carpocapsa) pomonella). 



This pest was responsible for the destruction of such large quantities 

 of apples during the years just prior to 1904 that it was feared apple- 

 growing on commercial lines would have to be abandoned. Paris green 

 was the spray used then, and, from an average crop', 35 to 50 per cent, 

 of sound fruit was regarded as a fairly good return. With the 

 introduction of arsenite of lead, about 1906, the quantity of sound fruit 

 increased to fully 80 per cent. The use of arsenate of lead commenced in 

 1907, and the results obtained since then by the judicious use of this 

 mixture have been so highly satisfactory that, in many instances, 98 

 per cemt. of sound fruit has been harvested. Owing to the efficiency 

 of arsenate of lead, the bandages formerly employed to act as traps in 

 which to catch the grubs have been dispensed with, and the work of 

 destroying natural harbors, such as loose bark and crevices in the trees, 

 has ceased to be regarded as important in orchards that are kept 

 thoroughly sprayed. 



Several brands of arsenate of lead were on the market a few years 

 ago, and, although analyses showed that they contained almost equal 

 quantities of poisonous matter, some were proved ito be more effectual 

 as insect destroyers than others, consequently only a few of the best 

 brands are oiow available. Provided the powdery residue or deposit 

 of two sprays remaining on the foliage and fruit after the air has dried 

 off the moisture be equally poisonous, the more adherent and cohesive 

 one will be the more efficacious as an insect destroyer. These properties 

 enable the powder, while maintaining the union of its own particles, 

 to stick to the tree, and, having once dried, it is not afterwards seriously 

 affected by rain. The powder thus retains its position on the tree for a 

 considerable time, and expands with the growth of the leaves or fruit, 

 as the case may be. The superiority of arsenate of lead over 

 arsenite is due to the deposit of the former being a powder as described, 

 while that of the latter is a thin film, which cracks and drops off as the 

 fruit expands, and is more easily washed away by rain. 



In order to determine the times to apply the first and subsequent 

 sprays for the codlin moth, it is necessary to understand its life history, 

 and to know its methods of attacking the fruit. It hibernates in the 

 larval stage under loose bark or in other crevices in the tree, and occa- 

 sionally in the soil near the butt of the tree. A certain number pupate 

 in early spring, and emerge from the chrysalides as moths about the 

 time the petals of the flowers are falling. The females commence to lay 

 their eggs a few days later on the young fruit clusters, often before their 

 calyxes close, and on the leaves near them. We know that a certain, 

 sometimes a high, percentage of grubs enter the fruit through the calyx 

 end, therefore it is reasonable and logical to conclude that the best 

 time to apply the first spray is after the petals of the flowers have 

 fallen, but before the calyxes close. When the first spray is applied 

 at this time, the residue of the mixture adheres to the nectar remaining 

 in the nectary, and, when the sepals close up, the poisonous matter 

 practically lines the cavity of the calyx. ISTot alone are the first-hatched 

 grubs prevented in this way from entering the fruit, but, as arsenic 

 retains its effectiveness for a considerable time, subsequent attacks would 

 also be repulsed, with considerable loss to this enemy of the fruit-grower. 



The illustrations in Plate 181 depict three stages of the young fruit 

 of the Duchess of Oldenburg variety after the fall of the petals. Pig. 1 



