AGRICULTURAL EXPERIMENT STATION. 213 



Spread of Trypeta from Variety to Variety. 



Trypeta has been in the orchard of Hon. Samuel Libby, of 

 Orono for the last three years at least, but has confined its depre- 

 dations to a single Benoni tree. They are not scarce on that tree 

 as the writer has taken as many as three larvae from a single 

 apple. Within twenty-five feet is a Wealthy, fifty feet a Red 

 Astrachan and sixty feet a Nodhead, all varieties badly infested 

 in other other orchards in the State, but not a single maggot has 

 been detected in any of them. 



The same is true in Mr. Webster's orchard on the other side of 

 the river, where Trypeta has for several years feasted on Golden 

 Russetts while several other varieties equally inviting have been 

 exempt. Last season the Golden Russett did not bear and the fly 

 transferred its depredations to another variety near by. Within 

 100 rods of Mr. Webster's orchard, across the river from it, is 

 another orchard where early sweet and sub-acid varieties are 

 grown, yet Trypeta has not been detected. 



Mr. Atkins says : "That in Bucksport some trees of a variety 

 will be infested while other trees of the same variety in the same 

 orchard are exempt." 



The slowness with which this pest spreads from tree to tree, and 

 variety to variety in an orchard, and from orchard to orchard, has 

 been noticed by Comstock and others, and when any attempt has 

 been made to explain it, it has been by saying the insect is fas 

 tidious in its tastes. It is probably true, taking the whole State 

 or country, that the pest is worse upon summer sweet and sub- 

 acid varieties, but it does not confine itself to these. The lonor 

 list of varieties we publish, which are infested, shows a wide 

 range of occurrence in sweet, sub-acid and acid, summer, autumn 

 and winter fruits. The history of this insect in Maine shows that, 

 it was first introduced from adjoining states in early imported 

 fruit. It has gradually spread from the early varieties until 

 neither sweet, acid, sub-acid, early or late apples are exempt from 

 its attacks. 



The larvae from early apples enter the pupa state earlier and 

 emerge earlier in the spring, or from the earlier apples there would 

 be generated an early race of flies. These would appear under 

 ordinary circumstances when the early apples were ready to receive 

 the eggs, and before other varieties were far enough advanced, 

 and the early apples would continue to be infested from vear to 



