New Pest Response Guidelines - aphis - US Department of Agriculture

Pest Information
Dendrolimus sibiricus
Adult
Female moths will produce a sex-specific pheromone to attract males and mate
one to four days after they emerge (Khrimian et al., 2002; Klun et al., 2000;
Liu and Shih, 1957). Mating normally takes place at night between 1am and
3am (Liu and Shih, 1957). Right before mating, both males and females will
vibrate their wings. Wing vibrations are more intense in males. Males will
immediately approach a female and dance around it while vibrating their wings
and mate. During mating, a male and a female moth pair together at their
abdomen, aligning their bodies with heads facing in opposite directions. They
will remain in this position for an average of 13 hours before they separate. A
few hours after they separate, the female starts laying viable, fertilized eggs
(Liu and Shih, 1957). If females do not mate during this time, they will start
laying unfertilized eggs, however, virgin females that are laying eggs can
eventually mate and produce viable, fertilized eggs (Liu and Shih, 1957). Eggs
are laid in clusters or in straight lines on the pine needles or branches. A female
will normally lay between 165 to 501 eggs during her lifetime, most of them
(60%) the first day, right after mating (Liu and Shih, 1957). Oviposition
normally takes place at night between 7 and 10pm and last on average 8.1days
after which the females die (Liu and Shih, 1957).
Larva
Newly emerged larvae will normally remain grouped during the first instar
stage. When disturbed, they will produce a silky thread and drop to the forest
floor where they will rapidly move in characteristics side to side twisting
movements. This behavior is unique to the first instar larvae. Larvae of other
instars will not drop and twist when disturbed, instead, they will curl in a Clike
position and move slower than the first instar larva (Liu and Shih, 1957).
First instar larvae feeds on the outer surface of pine needles, rarely consuming
the entire needle. As the larvae grow, the entire needle will be consumed (Liu
and Shih, 1957). When ready to overwinter (normally III or IV instar) the
larvae migrates to the forest floor where they will search under the forest litter
for a suitable place (normally with 1 to 7 cm of moss or leaves) to overwinter.
If there is no forest litter or moss near, the larvae will overwinter in crevices of
stones or in larch roots (Galkin, 1993). Overwintering rarely happens in the
soil. Larvae will overwinter on average at a 25 cm radius from the tree trunk
with a maximum of 82cmts on the east side of the trees (Liu and Shih, 1957). If
the affected forested area is in a hill, the majority of overwintering larvae are
found at the top of the hill and not the base (78 larvae were found around 17
trees sampled on top of a hill compared to 26 larvae in the same number of
trees at the bottom of the hill) (Liu and Shih, 1957). When the temperature is
around 10ºC in the spring, the overwintering larvae will break diapause and
start migrating from the forest floor to the tree tops.
2-32 Dendrolimus Pine Moths 12/2012-01