The Zimmerman pine moth, Dioryctria zimmermani (Grote), 
as presently identified, is widely distributed in the United States 
and southern Canada. In the northern part of its range, the 
larvae feed in the cambial region and outer xylem under the bark 
of limbs and trunks of all commonly grown species of pines. In 
the Southeastern States, it feeds almost exclusively within dam- 
aged cones of loblolly pine. The adult is gray and has a wing- 
spread of about 25 to 37 mm. The forewing is mottled with zig- 
zag lines of red and shades of gray. Mature larvae from the 
Northern States are pink to greenish and covered with small 
black dots, each with a black seta; they are about 18 mm. long. 
Larvae from the Southeast differ by having the abdominal seg- 
ments bluish-black above. These differences in habits and ap- 
pearance of the larvae suggest that not one but two closely re- 
lated species are involved (565). 
Adults in the Northern States emerge from mid-July to mid- 
August and deposit their eggs at the edges of wounds, on resin 
masses, in bark crevices, or on terminal buds. Hatching occurs 
in about 8 to 10 days and the young larvae, without feeding, enter 
bark recesses and spin hibernaculae. Here they remain until the 
following spring. Feeding begins in May or June, first on the 
bark, then by tunneling in the cambium area of new growth on 
terminals or laterals. Damaged terminals usually become “‘fish- 
hooked” and turn yellowish-green. Toward the end of June, the 
larvae leave the new growth and tunnel beneath the bark in the 
whorl area, girdling branches and leaders. Pupation occurs in 
resin masses or in the tunnel. Dead tops, dead branches hanging 
on trees (fig. 139), and burl-like growths on trunks above gir- 
dled whorls and pitch masses (fig. 140) are evidence of attack. 
Infested trees tend to be reattacked again and again, thus be- 
coming so-called brood trees (614). 
In the Southwest, the winter is spent as young larvae in ter- 
minals or second-year cones. Older larvae feed in second-year 
cones only. Entrance holes in cones are usually filled with !oose 
frass but are not surrounded or covered with resin or webbing. 
Pupation occurs deep within hollowed out cones and the adults 
appear in September and October. Infested cones stop growing 
and turn brown when about half to three-quarters grown. 
Zimmerman pine moth damage has been especially serious in 
Christmas tree plantations of Scotch, red, and Austrian pines in 
the North Central States and southern Canada in recent years. 
Dioryctria amatella (Hulst.) occurs from Virginia to Florida 
and westward through the Gulf Coast States to Texas and Arkan- 
sas. It appears to be most closely associated with longleaf pine, 
the larvae attacking both the terminals and second-year cones; 
however, it also attacks second-year cones of loblolly, slash, and 
shortleaf pines, and stem and branch galls of southern fusiform 
rust on loblolly and slash pines. The adult (fig. 141) has a wing- 
spread of 27 to 32 mm. and the forewing is dark-brown to black, 
with prominent patches and zigzag lines of white. Mature larvae 
are greenish-white with brownish markings above; they are 
about 25 mm. long. 
Winter is spent mostly as young larvae at the base of first- 
year cones or under expanded terminal needles—occasionally as 
356 
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