1896 The Cornell Reading-Courses 



it gradually spread westward, reaching California about 1874. The losses 

 caused by the codling moth are often severe; from one-fourth to one-half 

 of the crop in the improtected orchards of New York State is sometimes 

 destroyed in this way. As a rule the percentage of infested apples is 

 greater during years when there is a short crop than when the yield is 

 large. The explanation of this is simple: when the crop is small there 

 are more caterpillars in proportion to the number of apples. The esti- 

 mated apple crop for New York State in 1914 was 6,500,000 barrels. 

 Asstmiing that one-fourth of the crop was destroyed by the codling moth, 

 the production of that year would have been 8,666,666 barrels. Thus 

 the loss was 2,166,666 barrels, or $2,166,666, estimating these apples at 

 $1 per barrel. According to the census of 1910 there were 11,248,203 

 bearing apple trees in New York State. It is estimated that 40 per cent 

 of these trees are sprayed at least once for the codling moth. The cost 

 of this work is not far from 10 cents per tree, or about $45,000. The sum 

 of the loss of the fruit and the cost of spraying necessitated by the codling 

 moth is at least $2,211,500, which represents the annual tax levied on 

 New York State by this insect. 



Owing to its great economic importance the codling moth has received 

 more attention at the hands of entomologists than any other insect 

 injurious to fruits, and the facts of its life history have been worked out 

 with greater detail. Ranging throughout North America wherever the 

 apple is grown, it has adapted itself to the variations in climate by modify- 

 ing the length and number of generations produced annually. In New York 

 State there are one brood and a partial second brood annually, but in 

 the Lake Champlain district the second brood is so small as to be of little 

 importance. The insect is, therefore, not so destructive in this State 

 as it is farther south' where the longer growing season permits more 

 generations to develop. 



Life history. — In New York the codling moth passes the winter as 

 a full-grown caterpillar, curled up in a tough silken cocoon under flakes 

 of bark or in crevices in the trees. While the greater niimber find suitable 

 winter quarters on the trees, a few occasionally secrete themselves- in 

 piles of rubbish, in adjacent fences, or in other dry, protected places. 

 Occasionally on yoimg smooth-barked trees the caterpillars do not find 

 a suitable hiding place on the trunk or branches, and they may then be 

 forced to spin their cocoons under stones or in the space between the 

 trunk and the soil; it is very doubtful if any of the caterpillars in these 

 situations survive the winter. The cocoon measures from one-half to 

 five-eighths inch in length and is composed of a thin tough layer of silken 

 thread, in which is mixed bits of the bark or wood to which it is fastened. 

 It is lined with white silk and the outside is rendered inconspicuous by 

 the addition of bits of dirt and bark 



