320 



APPLIED ENTOMOLOGY 



attack the early varieties of apples. Later appearing flies may sometimes be 

 found until into September, and these select fall and winter fruit for egg laying. 

 Some varieties of apples are much more subject to the attacks of this insect 

 than are others. 



Egg laying begins about 20 days after the fly emerges and probably continues 

 for 2 or 3 weeks, the total number of eggs laid being several hundred. These 

 are inserted singly under the skin of the apple and preferably where the surface 

 is not exposed to sunlight. They hatch in 4 or 5 days and the little whitish 

 maggots tunnel through the pulp of the fruit in all directions. At first, the 

 rapid growth of the fruit may fill up these tunnels, but after a time the walls 

 around the tunnels instead of filling in, turn brown and the fruit softens, decay 

 may follow, and the entire apple is spoiled for sale. The maggot (Fig. 339) has 

 no real jaws with which to tunnel but has a pair of small hooks at the mouth 

 opening with which the pulp is rasped and torn, freeing the juice upon which 

 the insect feeds. 



/ 



FIG. 338. FIG. 339. 



FIG. 338. Adult Fly of the Apple Maggot (Rhagoletis pomonella Walsh), slightly 

 over three times natural size. (Reduced from Nova Scotia Dcpt. Ayr. Bull. 9.) 



FIG. 339. Puparium (left) arid full-grown maggot (right) of the Apple Maggot. 

 About three times natural size. (Modified from Nova Scotia Dept. Agr. Bull. 9.) 



The length of the larval stage depends upon the temperature and upon the 

 ripeness of the fruit. In warm weather and with rather soft pulp, about 2 to 4 

 weeks is usually the time necessary, but with colder weather and in late-maturing 

 varieties, growth toward maturity is delayed and some maggots may possibly 

 even winter in this stage in extreme cases. When the larva has completed its 

 feeding, however, it leaves the fruit (usually as this becomes ripe) and enters the 

 ground where it burrows below the surface often some distance, and pupates in 

 a puparium (Fig. 339) remaining here until the following summer when the flies 

 emerge. Where infested fruit is gathered and stored before the maggots leave it, 

 the puparia may be found on the bottom of the barrels or bins where the fruit is 

 kept. A few of the earlier pupating maggots appear to transform to flies the 

 same season, giving a second generation, but so few do this that it is of little or no 

 economic importance. On the other hand, a few seem to require 2 years for 

 the completion of their life history. 



The amount of injury caused where this insect is abundant is often very great, 

 particularly with early apples, a large percentage of which may prove entirely 

 worthless. Among the varieties which suffer severely are the Early Harvest, 

 Gravenstein, Porter, Red Astrachan, and Wealthy, sweet and sub-acid summer 



