6 MISC. PUBLICATION 16 8, TT.S. DEPT. OP AGRICULTURE 



The maggots have been found to distribute bacteria and molds 

 through the interior of the fruit, causing the flesh to rot and break 

 down and, in badly infested fruits of the early varieties, to drop 

 prematurely. In the case of fruit of winter varieties which fails to 

 drop, the maggots are usually killed by the pressure of the rapidly 

 growing fruit, although the tunnels remain as brown woody streaks 

 through the flesh, rendering the fruit less suitable for cooking or 

 eating. Most of the damage is done on sweet or subacid varieties of 

 summer and fall apples, although winter varieties do not entirely 

 escape. A small amount of injury results from the egg laying of 

 the flies. The flesh immediately surrounding the egg punctures 

 sometimes fails to grow, causing dimplelike depressions in the 

 surface. 



CAUSE 



The apple maggot or railroad worm is a footless white or cream- 

 colored larva, usually about one third of an inch long when full 

 grown. The adult form is a fly, somewhat smaller than a house fly, 

 which emerges from the soil during late June, July, or early August, 

 depending on the locality. The flies make tiny punctures in the skin 

 of the fruit and place their eggs just underneath. The eggs have a 

 short period of incubation, and in hot weather they hatch in from 

 4 to 6 days. The period spent by the maggot in the fruit varies 

 greatly but may be as short as 2 weeks. When mature, the maggots 

 leave the fruit, which by this time has fallen to the ground, and 

 enter the soil, forming puparia which resemble grains of wheat. 

 Within the puparia the insects transform to the adult stage and 

 emerge the following summer or sometimes the second summer. 



CONTROL MEASURES 



Since much of the infested fruit comes to the ground as windfalls, 

 and the maggots rarely leave until some time after the fruit has 

 fallen, the collection and destruction of drop fruit will do much to 

 control the pest. The benefits of this practice, however, are not evi- 

 dent until the following season. 



Satisfactory control of the insect has also been obtained by spray- 

 ing the trees with lead arsenate at the proper time in the summer, 

 thus killing the adults before they lay their eggs. Usually two appli- 

 cations of lead arsenate at a strength of 1 pound in 50 gallons of 

 water, with an interval of approximately 2 weeks between, have 

 been sufficient. In view of increasing difficulty with spray residue, 

 it is impossible at the present time to recommend this treatment, 

 although with the use of effective washing machinery the satisfac- 

 tory removal of the residue may be possible. Current recommenda- 

 tions of the Bureau of Entomology or of State experiment stations 

 should be used as a guide in working out a control program. 



Recent experiments by the New Hampshire Agriculture Experi- 

 ment Station ^ have shown that if infested fruits are held con- 

 tinuously at 32° F. for 1 month, practically all of the eggs and mag- 

 gots are killed. With a longer period of exposure, this method of 



3 Personal communication from G. F. Potter to D. F. Fisher, 1932. 



