214 MAINE STATE COLLEGE 



year. If the early apples did not bear, or from arrested or accel- 

 erated development the flies appeared earlier or later than their 

 accustomed rariety, they would be forced to find a new nidus for 

 their eggs. Let us suppose this to be a later variety ; then, as 

 this variety matures later, the larvae would enter the pupa state 

 later, and appear the following spring a later race of flies. Our 

 observations show that the flies are on the wing from early July 

 until frosts ; that the flies continue to emerge for a long time, or 

 that there are several races of flies appearing at different times. 

 A mild winter might force the late pupae and convert them again 

 into an early race, which will explain the disappearance of larvae 

 from a later variety and their appearance in an earlier variety. 



In some orchards the flies appear later and affect the later vari- 

 eties worse than the earlier. This may be because the later fruits 

 were first affected and the flies have continued in them, or the loca- 

 tion of the trees or the nature of the soil may give unfavorable 

 conditions for early development. The above facts illustrate the 

 erratic habits and wonderful adaptability of Trypeta, and must 

 impress us with the fact that we have a formidable pest with which 

 to contend. 



We believe that each tree usually produces the flies that infest it. 

 The flies were thick early in July on Early Harvests, but at that 

 time none were found about the trees of later varieties. Later in the 

 season the fruits of the fall and winter varieties became infested. 

 The Trypeta fly is not adventurous, does not roam about to gratify 

 the requirements of a fastidious appetite, nor does it stay so closely 

 at home because it is over particular about what it eats. It is 

 rather easily pleased, contented with what is set before it, be it 

 ^oild haws or Early Harvests. It clings from year to year to the 

 variety chance has thrown in its way, and does not abandon it, 

 until by over-increase or want of bearing, it is forced to find . 

 another nidus for its eggs. 



In Illinois though common in wild haws it has not until recently 

 spread to cultivated fruit. It probably left the haws in the P^ast 

 because in the settlement of the country the wild haws were cut. 

 In Michigan it has been forced to infest wild plums and cherries. 

 These things do not show fastidiousness but adaptability in a won- 

 derful degree. Certainly an insect contented in wild haws would 

 revel in any kind of a cultivated apple. The fact that the pest 

 has spread in our orchards slowly to apples of all flavors and times 

 of maturity shows an alarming power of adaptation to new food 



