6 N. H. AGR. EXPERIMENT STATION, [Bulletin 171 



PAGE 



The duration of the pupal stage is widely variable. The 



species exhibits both a one-year and a two-year life cycle 83 



In the one-year life cycle the pupal stage occupies, approxi- 

 mately, 300 days. Late maturing larvae do not neces- 

 sarily transform late the following season, but apparently 

 tend somewhat toward moderately retarded emergence, 

 while the reverse is true of early maturing larvae 83 



A proportion of individuals require an extra year for the 

 pupal stage. This may be true of early as well as late 

 maturing larvae. Emergence of adults from these pupae 

 occurs at the normal time the second summer 84 



Pupae, once successfully formed, are measurably resistant to 



unfavorable surroundings 85 



Description of Stages 87 



Experiments in Control 89 



Control measures directed against the adult require careful 



interpretation because of the habits of the species 89 



Poison bait sprays, in three years' extended trials in New 

 Hampshire, have entirely failed to insure satisfactory 

 protection of fruit from attack by the maggot. With 

 five or more applications the apples often show abund- 

 ant egg-punctures. Even with ten applications the 

 fruit may be worthless. The adults are not materially 

 attracted to the bait, as so far devised, and are not 

 poisoned in sufficient numbers to render the treatment 

 a definite benefit in the absence of other measures of 

 control 91 



There may be some indirect benefit from ordinary- orchard 



spraying, probably in part through lessening drops .... 102 



The critical point in the larval stage is the fact that fruit 

 must drop and reach a favorable degree of mellowness 

 before the larva can mature and leave it 103 



A successful measure taking advantage of the above fact is 

 the collection of drops at sufficient intervals to prevent 

 them from decaying on the ground 103 



Farm livestock may be used to accompHsh the same pur- 

 pose. Satisfactory use has been made of hogs, sheep 

 and cattle. Hogs sometimes injure trees 104 



