beneath loose bark scales. There are four or five generations per 
year (347, 346, 709). 
Infestations usually occur on medium to large trees in moder- 
ately to densely stocked stands, but they are also occasionally 
found on seedlings and saplings. Because of the lateness of the 
season when the larvae are most active, heavily infested trees 
may remain without needles throughout the winter. Heavily de- 
foliated trees are weakened and rendered susceptible to attack by 
bark beetles, especially [ps spp., and wood borers. Tree mortality 
as a result of defoliation has not been reported. Several outbreaks 
have been recorded in Florida and Texas in recent years, most of 
which subsided after one season. A polyhedral virus disease and 
several parasites and predators apparently are highly effective in 
bringing outbreaks to an early end. 
A number of other species of Neodiprion also occur in eastern 
forests: N. nigroscutum Middleton occurs on jack pine in the 
Lake States and Ontario. Full-grown non-feeding larvae are gray- 
pink with a tinge of yellow on the lateral margins (49). N. piniri- 
gidae (Norton) feeds on pitch and shortleaf pines from New 
Jersey to Maine. The full-grown larva is dull green, has a double 
longitudinal black line on the dorsum and a broken black stripe 
on each side. Sometimes a double row of black dots occur below 
each lateral stripe. N. warreni Ross occurs on shortleaf pine in 
Arkansas. Full-grown larvae have almost entirely black heads and 
broad black longitudinal stripes on the dorsum. An outbreak was 
recorded in 1958. N. merkelit Ross attacks slash pine in southern 
Florida. The head of a full grown larva is reddish above the eyes 
and sooty black below, with a reddish infusion. N. hetricki Ross 
has been observed feeding on loblolly pine in Virginia and pond 
pine in South Carolina. The head of the larva is black, subdorsal 
lines are solid, and supradorsal lines are composed of separate 
spots or beaded lines. N. compar (Leach), feeds on red and jack 
pines in southeastern Canada, Virginia, North Carolina, and 
Georgia. N. maurus Rohwer occurs on jack pine in southeastern 
Canada and the Lake States. 
The genus Diprion Schrank is represented by only three species 
in the United States and Canada and all three are of foreign 
origin. 
The introduced pine sawfly, Diprion similis Hartig, was first 
recorded in North America at New Haven, Connecticut, in 1914. 
It now occurs from Maine to Virginia, in the Central and Lake 
States, and in southern Ontario and Quebec. White pine appears 
to be its favored host but Scotch, red, jack, and mugho pines are 
also commonly attacked. Full-grown larvae (fig. 182) are about 
20 mm. long. The head is shiny black and the body is dark brown 
or black with a double black stripe down the dorsum and black 
and yellow spots on the sides. 
Winter is spent in the prepupal stage. Pupation occurs in early 
spring and the adults appear from May to mid-June. The females 
are reported to possess a potent sex attractant (161). Eggs are 
laid in rows of about 10 eggs each and deposited in slits cut in the 
edge of old needles. Young larvae feed gregariously; older ones, 
singly. First generation larvae feed on old needles only, while the 
larvae of later generations eat both new and old needles. Young 
450 
