Newly-hatched larvae spin resin coated, tentlike webs between 
needle sheaths and the stems of current year’s growth, then they 
bore through the sheaths and mine the bases of the needles. About 
mid-summer, the larvae move to buds and construct new resin 
coated webs. At first, these webs glisten brightly; then they 
solidify into yellowish-white masses. Feeding ceases in August. 
Winter is spent in the larval stage in a feeding tunnel in a bud. 
When activity is resumed in April, the larvae move to undamaged 
buds and new shoots, construct new tents, and resume feedings. 
During this period, a single larva may feed on more than one 
bud or shoot. Larvae reach maturity in May, and pupation occurs 
inside the burrow or tent in late May or June. Two or three weeks 
later, the larva works its way out of its chamber. There is one 
generation per year. 
The most important and permanent damage to trees results 
from spring feeding. Shoots weakened by larval tunneling fall 
over, but continue to grow. This results in the formation of 
crooked trunks and branches or “post horns.” The killing of ter- 
minal and lateral buds results in dead, spike tops. The develop- 
ment of adventitious buds below this dead portion often causes 
the formation of dense, bushy growth the following season. The 
killing of the terminal bud and the development of several lateral 
buds into competing leaders results in forked stems. All open- 
grown young trees of susceptible species below a height of 20 to 
25 feet are subject to attack and damage. Taller trees or trees 
growing in closed stands are usually not seriously damaged. 
Climate is an important factor affecting the distribution and 
abundance of the European pine shoot moth. Overwintering lar- 
vae are killed by temperatures colder than about —20° F. Warm, 
dry summers followed by mild winters permit maximum survival. 
Rate of tree growth is also important as damage is usually most 
severe on slow-growing trees. Introduced and native species of 
parasites normally destroy about 10 percent of the population. 
Five introduced species have become established: Orgilus obscur- 
ator (Nees), Temelucha interruptor (Grav.), Hulimneria rufife- 
mur Thom., Pimpla turionellae (L.), and Tetrastichus turionum 
Htg. O. obscurator appears to offer the most promise. Yates 
(797) published a key to the nearctic parasites of the genus. 
The planting of susceptible pines on good sites, “snow-depth 
pruning,” and Christmas tree shearing are helpful in reducing 
damage (526). Fumigation in the spring has provided a degree 
of control on seedlings and larger ornamental specimens (135). 
The reader should consult Agricultural Handbook 331 for details 
on registered control methods. 
Many publications have been issued on the biology, ecology, 
and control of the European pine shoot moth. In addition to those 
cited in preceding paragraphs, there are several others that are 
of ‘special interest (273, -328, 529, 5380, 599, 755). Articles by 
Heikkenen !3 and Torgerson !* are also pertinent. 
Rhyacionia adana Heinrich has been recorded from Massachu- 
setts, Pennsylvania, Virginia, Michigan, Wisconsin, and Ontario. 
13 Heikkenen, H. J. 1963. Influence of site and other factors on damage 
by the European pine shoot moth. PhD thesis, Univ. of Mich. 
14Torgerson, T. P. 1964. The binomics of the European pine shoot moth 
in Wisconsin. PhD thesis, Univ. of Wis. 
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