AGRICULTURAL EXrERLMENT STATION. 123 



THE FAT.L CANKEIJ AVOKM. 



Anisojjteryx pometaria, Harris. 



When we first began to observe this insect in 1887 it was not 

 very abundant about Orono and did no material injury. It gradu- 

 ally increased from year to year and in 1893 had become so abund- 

 ant as to do much damage to orchards and shade trees. The 

 foliage of trees on the college campus and in Orono were so badly 

 eaten that it was feared they would die. For some unknown reason, 

 probably from the increase of parasites that prey upon this species, 

 it almost entirely disappeared during 1894 and has given no trouble 

 whatever about Orono in the summer of 1895. The insects seem 

 to be migrating or passing over tlie State like a slowly moving wave 

 from the north toward the south. Its depredations have gradually 

 spread down the Penobscot valley. In 1893 they were very abund- 

 ant in Arnold and Prospect and this season (1895) they are doing 

 so much damage to the shade trees in Thomaston that a town 

 meeting will be called to consider the means necessary to check them. 

 Mr. E. P. GeoFge, President Thomaston Improvement Company, 

 writes that "canker worms appeared upon a few of our fruit trees 

 about four years ago. They have increased in numbers each year and 

 gradually spread to the elms until this year fully three-fourths of the 

 eight or nine hundred elms and fruit trees in the village were com- 

 pletely infested and deprived of their foliage by the end of June." 

 The trees about Orono were not killed. They no doubt suffered a 

 severe shock and the growth for a season or two was greatly checked 

 but they seem to have regained their usual vigor. It took the 

 worms about five years to reach the period of greatest numbers at 

 Orono and if they have the same experience at Thomaston with them 

 they will not be so abundant next season. It is well known to ento- 

 mologists that insects have gradual periods of increase and then 

 suddenly decline. We had a very good example of this in Maine in 

 the case of the Forest Tent Caterpillar, which is fully explained 

 byrapid increase of parasites, (see Station Report 1890, page 138.) 



