REPORT OF THE STATE ENTOMOLOGIST I913 6l 



FOREST TREE PESTS 



Forest tent caterpillar (Malacosoma disstria Hubn. ) . 

 The depredations of this species recorded in 1912 have been con- 

 tinued on a more extended scale the present season. The cater- 

 pillars defoliated a number of acres of woodland in Roslyn and 

 Jericho on Long Island, were abundant in Putnam and southern 

 Dutchess counties, attacked maples at Granville, Elizabethtown and 

 Ogdensburg and defoliated extensive tracts of poplar in Franklin 

 and Clinton counties. 



The last of May and early in June many of the oaks in Roslyn 

 and Jericho were defoliated, a few of the caterpillars being only 

 half grown, must of them fully developed, and some, particularly 

 in the warmer, more advanced situations, had commenced to spin 

 their cocoons. The injury in this locality was practically confined 

 to the oaks. At Granville, Elizabethtown and Ogdensburg the 

 caterpillars were most numerous upon the sugar maple, while in 

 Frankin and Clinton counties there was a marked preference for the 

 poplar (Populus tremuloides), particularly the tops of 

 trees 30 feet or more in height. The feeding, in certain cases at least 

 was confined to the vicinity of water. The aspen or poplar was 

 the preferred food plant in this section, though willow, when stand- 

 ing near stripped trees, was eaten to some extent. The pin or 

 bird cherry was partly defoliated and evidently eaten by the cater- 

 pillars only when forced by hunger. Elms and Cornus close to 

 poplars were badly eaten or nearly stripped, respectively. The red 

 maple and birch were nearly exempt from injury, unless next to 

 defoliated trees. Pine, balsam and spruce, in fact all coniferae 

 observed, were practically unharmed, though numerous cocoons 

 were to be found among the needles (June 27th). The area of 

 serious injury in this section begins at about Rainbow lake, Frank- 

 lin county, and extends eastward through Clinton county nearly 

 to Lake Champlain. 



Natural enemies were observed at work both at Rainbow lake 

 and Chazy lake. At Rainbow lake a large Carabid beetle wrs 

 taken on a tree trunk some 4 feet from the ground. It was there 

 evidently in search of caterpillars. Numerous Tachinid and Sar- 

 cophagid flies were observed about the caterpillars and were pre- 

 sumably ovipositing thereon. A number of Hymenopterous para- 

 sites, particularly Pimpla species, were observed on the cocoons at 

 Chazy lake. 



The probabilities of continued injury another season can best 



