THE CODLING MOTH IN MASSACHUSETTS 71 



Based on work done by the Massachusetts Agricultural Experiment Sta- 

 tion and numerous other experiment stations, a brief summary of the know- 

 ledge of the prevention of spray-injury is here presented. If these several 

 factors are observed in practice, spray-injury can be reduced in severity. 



If, by well-timed early applications, the leaves can be kept relatively free 

 from scab, there will be less spray injury than is likely to occur on leaves 

 which are scabby when sprayed. 



A fine mist of spray, with no more than the minimum amount necessary 

 to wet the leaves applied, and that applied without unnecessary violence, are 

 conditions least likely to result in spray-injury. 



The safest time to spray with the lime-sulfur-lead arsenate combination 

 is on a cool day when the air is dry and before a rain. The conditions most 

 likely to result in injury occur on a hot day when the humidity is also high 

 and immediately following a rain. 



Either dry-mix sulfur-lime or sulfur dust is less likely to bum than is 

 lime-sulfur. 



The soluble arsenic, which is one of the causes of spray-injury in the 

 lime-sulfur-lead arsenate combination, is kept low in amount, making the 

 spray safer, if calcium caseinate is used. In filling the spray tank, the 

 calcium caseinate should be put in before either the lime-sulfur or the lead 

 arsenate, rather than to have the two latter meet and react in the absence 

 of the caseinate. The fact that the residue in the spray tank is ricli in 

 soluble and dangerous arsenic, makes it important that there be good agi- 

 tation and that the spray tank be cleaned frequently. 



Summary 



The codling moth is one of the most destructive insect pests of the apple, 

 and is present practically everywhere this fruit is grown. 



The apple is the favored food of this insect and all varieties are attacked. 

 Pears, peaches, cherries, plums, quinces, and walnuts are also infested. 



The injury to the fruit is caused by the larvae, or "worms", tunnelling 

 through it and also causing undesirable scars called "stings". 



The inconspicuous gray moths lay from twenty to forty small pearly- 

 white eggs during the two or three weeks of their life. TI>e eggs are laid 

 singly on the leaves, twigs or fruit. 



Newly-hatched larvae quickly enter the fruit, where they feed for about 

 three weeks. The majority of the first "worms" enter through the calyx 

 end of the apple while later in the season many enter through the side. 

 Young larvae sometimes feed more or less upon foliage before entering the 

 fruit. 



In Massachusetts, the codling moth has one complete generation and a 

 partial second, annually. 



The winter is passed as full-grown larvae within tightly woven cocoons. 

 These overwintering larvae include a part of the first brood "worms" and all 

 of the second. 



Pupation begins the last of April or early in May, about the time fruit 

 buds of the apple show pink. 



