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The Codling Moth In The Packing House

( Originally Published Early 1900's )


Thousands of dollars are lost annually by the fruit growers of Michigan through their neglect and carelessness in fumigating. their storage and packing houses. The codling moth, the most serious insect enemy of the apple, winters over in such sheltered places, as well as under the bark on the trees.

The larvae or apple worm crawls out of the apple in storage, and having found a suitable place, weaves about itself a cocoon. Towards spring the larvae changes to the pupal stage. The pupae is about half an inch long, varying according to age from a yellow to a brown color, and changing to a bronze hue just before the moth is to emerge. These cocoons are generally spun up under loose boards or under old rubbish. When weather conditions are right, the moth comes out of the cocoon, flies about and lays its eggs throughout the orchard. The eggs soon hatch out into larvae, which enter the apples.

Last summer I found apples badly infected with the codling moth larvae a week before the time to spray. I knew it was not time to spray as I was carrying on an experiment in the orchard to determine the flight of the moth.

I found the cause of this early infection in the packing house. To my surprise, the crates which were stored there over winter, were covered with cocoons of the codling moth. Upon entering and jarring the crates a cloud of moths blew about and out through the doors to lay their eggs in the orchard. The majority of the moths had flown at this time. I made an estimate of the number of cocoons and found that no less than 4,000,000 larvae were hatched out from this packing house.

You all know that a plant grown in a green house or some protected place, will come to maturity earlier in the spring than one grown out of door. The same was true of these moths that had been reared in the packing house. They hatched out earlier, on account of the warmer and more sheltered conditions under which they lived. As a result, the orchard was full of moths before a spray had been applied. Reasoning along the same line we can say, those cocoons spun up in cellars or storage houses would hatch out later than those in the orchard, be-cause of the cold and dampness. This brood would infect the orchard later in the year than those hatching out in the orchard.

Sprays are recommended to be applied at certain times. This time is the period when the larvae are present from eggs laid from moths reared under orchard conditions. Now we do not spray for this early brood which hatches out in the packing house or a later brood which hatches out in storage cellars. Instead, we resort to a simple method of fumigation or burning of sulphur. This fumigation should be done early in the spring before the approach of warm weather. Where building can be closed up tightly, 5 pounds of sulphur to 1,000 cu. ft. of air space is sufficient, but in more open houses where every crack cannot be sealed up 10 pounds or even more should be used.

In conclusion, I would advise every grower to acquaint himself with the cocoon and moth and be able to detect it. If he is not sure of its presence, fumigate, as an ounce of prevention is worth a pound of cure.

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