New Pest Response Guidelines - aphis - US Department of Agriculture

Pest Information
Larva
After 16-25 days, the first instar larvae will emerge and start feeding on the
outer edges of young needles, progressively feeding until the needles are
completely consumed (Ciesla, 2004). The larvae will molt two or three times
during the fall feeding season. At the start of the winter season, the fourth or
fifth instar larvae will move down from the trees to the forest undercover
where they will burrow beneath the leaves, forest litter or soil and remain
dormant during the entire winter season (Heitland, 2002). Larvae will begin
diapause after their third instar. Larval diapause is triggered by the
photoperiod, usually when the day length is less than 12 hours for an average
of 38 days and it is inhibited with longer days, when the day length is more
than 17 hours (Geispits et al., 1972). Before diapausing, the larva will
gradually decrease its feeding and locomotion activity and excrete the gut
content (Geispits et al., 1972; Pszczolkowski and Smagghe, 1999). When the
spring starts the following year, and the day length is more than 17 hrs, the
larvae will climb back to the tree and resume their feeding activity until ready
to pupate. It is during this time that the larvae cause most of the damage to the
trees because of their size and the quantity of food consumed during feeding.
Spring feeding can be as much as 3 to 5 times more per larva than fall feeding
(Ciesla, 2004). Before they pupate, PTL larvae will undergo two to three
additional molts in the spring.
Pupa
When ready to pupate, the seventh or eighth instar larvae will crawl several
hundred meters in search of a suitable pupation site, normally on the tree
crowns, bark and occasionally on the understory vegetation. During pupation
the larvae spin spindle-shaped cocoons with silk sometimes covered with pine
needles and twigs. Pupation starts in late spring (May-June) and will last
between four to five weeks (Melis, 1940).
Dendrolimus punctatus
Adult
In southern portions of the known range, e.g., Vietnam, MPC is reported to
have four generations per year, as follows: March to May; June and July;
August and September; and overwintering from October to March (Billings,
1991). The number of generations is variable, ranging from one to five per
year. In more northen latitudes there are generally fewer generations per year
(Figure 2-4 on page 2-20). Overlapping generations have been observed with
insects in several life-stages on the same tree, while coastal climates may allow
larvae to remain active throughout the year. Females lay an average of 300-400
eggs.
12/2012-01 Dendrolimus Pine Moths 2-19