10 Farmers’ Bulletin 1259. 
DISTRIBUTION. 
Leconte’s sawfly occurs throughout the eastern United States, the 
accompanying map (fig. 10) indicating localities from which the 
species has been recorded or specimens received. 
TREES ATTACKED. 
This species seems to have a preference for jack pine,? red pine,’ 
and scrub pine,* each of which furnishes a local host in some part of 
the eastern United States through- 
out which the insect occurs. Its 
attack is not limited to these spe- 
cies, however, for it is also found 
on or recorded from white pine,® 
scotch pine, loblolly pine,’ shore 
pine,® silver pine,® mugho pine,?° 
western yellow pine," longleaf 
pine,? Austrian pine,* and Amer- 
ican larch.1 
PERIODICAL OUTBREAKS. 
Leconte’s pine sawfly, like most 
insect enemies of forest trees, ap- 
pears and disappears periodically. 
For several years this species will 
be very abundant, then for a few 
years it will be rare. The cause 
Fic. 10.—Map showing localities where for this periodic disappearance has 
Leconte’s sawfly is known to occur. : 
not been determined, but the low 
records of parasitism indicate that some factor other than parasitism 
plays an important role. 
NATURAL ENEMIES. 
Eight species of insect parasites and an infectious disease have 
been found killing this sawfly. None of these enemies, however, has 
been found widely enough distributed or abundant enough to account 
for the periodic disappearance of the species, and it is certain that 
neither any nor all of these natural checks are sufficiently numerous 
or effective to justify disregard of the artificial control measures 
suggested. 
2 Pinus banksiana. ®P. monticola. 
3 P. resinosa. 10 P, mughus. 
4P. virginiana. uP, ponderosa. 
5 P. strobus. 2 Pp, palustris. 
6 P. sylvestris. 13 P. austriaca. 
7P. taeda. 14 Lariz americana. 
8 P. contorta. 
