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Poplar Borer - Saperda calcarata   
Helen Atthowe, Missoula County
Extension
  Larvae
Maggie Heide - Missoula County
Extension
 HOSTS: Aspen, cottonwood, poplars, willow. DESCRIPTION:
Larvae
are large, yellowish, round-headed grubs, 1- 3/8 inch; adults are gray
beetles with a central yellow stripe on the thorax and
yellow-black-stippled wing covers, 1-1/4 inch long. LIFE
CYCLE: The
poplar borer has an extended life cycle that likely requires three
years to complete; shorter life cycles may occur in warmer areas of the
state. Adult beetles may be present from mid-June through early fall,
and feed on bark of young twigs. After mating, females chew pits in the
bark and insert eggs. Most egg laying is concentrated in the middle of
the tree, particularly near existing areas of infestation. During the
first year, the young larvae spend the winter under the bark. In
spring, they enter the sapwood and heartwood where they feed for two
years, producing large, black, swollen scars on trunks and limbs.Throughout their period of feeding, they maintain an opening to the outside through which they push the boring dust. After the larval stage is complete, they form a chamber under the bark where they pupate and spend the winter. CONTROLS:
Because of
the long (probably three year) life cycle, poplar borer is particularly
difficult to control. Apply Carbaryl or Cyfluthrin to the trunk in July when adults are active.
Application should focus on existing areas of attack in the
middle of the tree where egg laying is concentrated.Insertion of 'borer crystals' (paradichlorobenzene) or injections of insect parasitic nematodes (Steinernema species) into active borer tunnels have given partial control of larvae. Individual trees may serve as "brood trees" which can infest other plantings. Removal of these highly susceptible trees should be considered. Most often, large, over-mature trees in open areas are particularly susceptible to attacks by this species. |
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