386 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 16 
PARASITISM OF THE EUROPEAN PINE SAWFLY, DIPRION 
c LOPHYRUS);SIMILE HARTIG, HYMENOPTERA, 
TENTHREDINIDAE, IN PENNSYLVANIA 1 
By E. A. Hartley 
N. Y. State College of Forestry, Syracuse, N. Y. 
Heavy parasitism of the European Pine Sawfly in America has ap¬ 
parently rendered this potentially injurious immigrant of little im¬ 
portance as a pest of our pines. Evidence of a prompt attack of this 
imported species by our native parasites was first reported by Dr. 
Britton 2 shortly after the discovery of the sawfly in America, when he 
reared the following native species: Pachyneuron ( Dibrachys ) nigro- 
cyaneus Nort. parasitizing 31%, and one specimen each of Hemiteles 
utilis 5 Nort., an Ichneumonid, a species of Cerambycobius, and a Tachina 
fly, Exorista petiolata Coq. In 1917 Dr. Britton 3 after a large collection 
of over-winter cocoons, reported 37% parasitism involving the following 
parasites: Pachyneuron ( Dibrachys) nigrocyaneus Nort., Monodonto- 
merus dentipes Boheman Dibrachoides verditer Nort., (Pteromalus), 
Delomerista n. sp., Cerambycobius sp. (probably new), Eurytoma sp., 
Hemiteles utilis Nort. and the Tachina, Exorista petiolata coq. Only 
the first three were in effective numbers. All of these parasites are natives 
except Monodontomerus dentipes which is a European species previously 
found in the United States. In the spring of 1917, Weiss 4 reported a 
parasitism of 90% by Mondontomerus dentipes for the European Pine 
Sawfly in New Jersey. 
Diprion simile was first noticed in the Philadelphia District in 1918 
when only a few larvae were collected on a small row of Pinus cembra . 
Scattered larvae were noticed on Pinus strobus and P. cembra in several 
parts of a large nursery during the three years following, but nowhere 
had they increased to destructive numbers, except perhaps, in about a 
half acre block of Pinus cembra in the summer of 1921 where the infes¬ 
tation was about evenly distributed thruout the block and heavy enough 
to cause noticeable defoliation. Larvae were conspicuous on prac¬ 
tically every tree. 
In early June of the following season (1922) the block of pines was 
again examined and a marked decrease in the infestation was at once 
noticed; for in spite of the presence of many over-winter cocoons on 
Contribution from the Bureau of Plant Industry, Harrisburg, Pa., and the New 
York State College of Forestry, Syracuse, N. Y. 
fifteenth Connecticut Report. Seventeenth Connecticut Report. 
4 Jour. Econ. Ent., Vol. X, No. 1, 1917. 
6 NowH. Tenellussays; Cushman&Gahan, Proc. Ent. Soc. Wash.,23:163,Oct. 1921. 
