F-519519 
FIGURE 144.—Larva of the 
pitch twig moth, Petrova 
comstockiana, in the twig 
of red pine. Pitch mass 
covers the opening to the 
larval gallery. 
resumed in May, and pupation occurs under the mass. There is 
one generation per year. Damaged twigs break off, leading to de- 
formation of infested trees. The braconid, Agathis pint (Mues.), 
has been a major factor in control (531). 
Petrova virginiana McD. feeds on jack pine in the Lake States 
and southern Canada. The larvae feed in and hollow out the ter- 
minals and adjacent lateral buds. Winter is spent as a larva in 
the large, central bud. Feeding is resumed about mid-May and 
pupation occurs in the bud in early June. Damage to terminals 
and lateral buds results in the death of an entire whorl, causing 
crooked stems and stag-headedness. 
Petrova albicapitana (Busck), the pitch nodule maker, occurs 
in all parts of North America where jack pine grows naturally. 
Scotch and lodgepole pines are also attacked. The adult is reddish- 
brown with grayish patches on the forewings, and has a wing- 
spread of 16 to 23 mm. 
Young pines from 1 to 5 feet tall are most heavily infested. 
Smaller ones are not attacked and taller ones are rarely injured, 
although signs of attack may be seen in trees up to 30 feet tall. 
Larvae feed singly under masses of pitch, some of which may be 
up to 115 inches in diameter, generally at an internode or fork. 
As they develop, their feeding may be extended almost to the 
pith. Two years are required to complete the life cycle, winter 
being spent in the larval stage. Pupation occurs under the pitch 
mass. 
When an attack occurs at the base of a growing terminal, the 
shoot may be girdled and killed, or the terminal may survive as a 
weakened, crooked trunk. Damage in jack, Scotch, and lodgepole 
366 
