126 PROCEEDINGS OF THIRTY-SIXTH FRUIT-GROWERS ' CONVENTION. 



removed, so taxing the vitality of the tree, and the excreted honey dew 

 produces a very objectionable gumming of the foliage and fruit. 



Contact insecticides must be used for the woolly aphis, but the lime- 

 sulphur solution, so valuable against scales, is not very effective for this 

 insect. The oil emulsions and nicotine washes give better results. 

 Something can be done towards controlling the top form by going over 

 the trunks and large limbs, very thoroughly, during the winter with 

 distillate emulsion. The object is to kill the colonies wintering in the 

 protection of the rough bark formation about wounds. The application 

 has to be very thorough to insure penetration. 



This winter treatment may not have killed all the colonies of the 

 woolly aphis, so nicotine applications may have to be made in the 

 summer. The root form of the aphis is not readily reached by any 

 treatment, but the crown can be largely protected by removing some 

 of the earth and pouring in a quantity of tobacco decoction. 



Of the chewing insects the codling moth is probably the most 

 important. This species is estimated to cause a 40 per cent loss to the 

 apple crop of the world. The codling moth passes the winter as a 

 mature worm or larva, well concealed and protected by a cocoon, not 

 always on the trees, but frequently in the ground, fences, and old 

 buildings. In the California coast districts these wintering-over larvae 

 do not pupate and emerge as moths until the middle of May, and then 

 not completely, for numerous moths appear even up to the middle of 

 June. After the appearance of the moths it is not long before eggs are 

 laid, and the young worms hatch some ten days later. The early eggs 

 are deposited on the upper surface of the leaves, and somewhat later the 

 under surface is frequently chosen. Not until the fruit rind has become 

 quite smooth and free from hairs are the young apples selected in 

 preference to the leaves. Eggs are seldom if ever laid in the calyx 

 cavity. 



The young larvae of- the codling moth, when hatching upon the leaves, 

 frequently have to crawl considerable distances before reaching an 

 apple, and. may feed to some extent on the foliage. The larva? have 

 been reared to maturity on the foliage alone. Many of these exposed 

 young may perish, and even after entering the fruit, death frequently 

 occurs from diseases and other causes. Of those individuals which 

 succeed in reaching the fruit, 50 to 75 per cent enter at the calyx. The 

 remainder bore in from other points, generally beneath a protection 

 such as the contact of a leaf or two apples. Once within the fruit a 

 more or less direct course to the core is taken. Here they feed and grow 

 until maturity. The seed are consumed as well as the tissues of the core, 

 and the destruction of the sap -conducting vessels often stops the further 

 growth of the fruit which fall, from this cause, during July and August. 

 The time required for the development of the larvae is about thirty days. 

 "When full grown the first generation worms emerge from the fruit and 

 shortly spin cocoons under some protection. Transformation into adults 

 takes place quickly, requiring ten to fifteen days. The moths so pro- 

 duced lay eggs which give rise to the second generation worms. The 

 eggs of the second generation are laid largely on the fruit, and 

 frequently in the most exposed places. The young larvae also appear 

 to manifest the same indifference to shelter and enter the fruit at any 

 point, choosing the calyx only by accident. Codling worms of the 

 second generation begin to appear strongly about the middle of August, 



