AGRICULTURAL EXPERIMENT STATION. 219 



ment. Leading backward from each spiracle to the last segment 

 of the body is a tube or air passage (trachea) which terminates 

 on the sloping surface of the last segment, in a caudal spiracle. 

 One of the caud'al spiracles enlarged is shown Plate III, Figure 

 Ic. At the junction of the fourth and fifth segments, and the 

 junction of the next to the last and last segments, are branch 

 tubes connecting the trachea?. 



Ptqm— Length 4.2 to 5.2 mm. (.17 to .21 in.) ; breadth 2 to 

 2.6 mm. (.08 to .1 in.). Pale yellowish brown. When the mag- 

 got assumes the pupa state it does not shed the larval skin. The 

 maggot contracts, assuming an oval form. The head segments 

 are entirely retracted so that the tubercles of the cephalic spiracles 

 project in front. The posterior end contracts but the caudal 

 t^piracles remain in view and the larval segments are easily made 

 out. The true pupa is found within this shrunken larval skin, or 

 in the language of the Entomologist the pupa is coarctote. The 

 pupa is a little more than twice as long as wide and barrel shaped, 

 the ends sloping about equally. The larva is about four times as 

 long as wide and the head end is very sloping and pointed. The 

 pupa is only twice as long as wide and nearly equall}^ sloping at 

 the ends. Otherwise the resemblance between the pupa and larva 

 is apparent. There is quite a variation in the size of pupae, some 

 are much longer and thicker than others and may be of females, 

 as the female flies are much larger than the males. (See Plate 

 JII, Figure 2.) 



Life History. 

 In early seasons, under favorable conditions, the flies in Maine 

 begin to emerge about July 1st, and earlier in the States farther 

 South. They continue to emerge all summer and are on the wing in 

 abundance until the middle or last of September and occasionally in 

 October. Early frosts check them. The flies lived three weeks in 

 confinement and will probably live longer in nature. They begin to 

 deposit their eggs in the early fruit by July 1st or earlier, and egg 

 laying continues while the flies are on the wing. The earlier races 

 of flies affecting the earlier varieties, and the later races the fall and 

 winter fruit. Each female is capable of laying, at least, between 

 three and four hundred eggs, which are inserted from time to time, 

 one in a place, by means of a sharp ovipositor through the skin of 

 the apple. The eggs being successively developed in the ovary of 



