Hylobius warreni (Curculionidae)

Warren's collar weevil


Adults:

Hylobius warreni adult. 8-11 mm in length, dull black and clothed with fine grey scales between the patches of white. Notice the snout which is characteristic of this family.



Larvae:

Hylobius warreni larva; it is apodous and similar in appearance to other Curculionid larvae. Larvae are white, legless, curled and practically indistinguishable from other larvae in this family. When larva is feeding around the root collar, dirt and shredded bark are packed together with resin from the tree to make a protective "tunnel". Trees less than 6 cm in diameter can be girdled.



Damage:

Root collar area damaged by Hylobius warreni feeding. Larvae which live for 2 years feed in the root collar area, often causing the cambium to be girdled. The adults live and lay eggs for up to 4 years, are flightless and feed upon the bark of small roots and twigs and on the needles of its hosts. Lodgepole pine can have chronic weevil infestations around the root collar area throughout the rotation. Trees less than 6 cm diameter can be girdled and killed. Otherwise, larger diameter trees seem to survive one or two feeding larvae.



Principal Hosts:

In B.C. the main host is lodgepole pine, but other recorded hosts include other Pinus spp., Abies, Salix, and Picea.

Economic Importance:

Mortality can result from root collar girdling as well as reductions in growth. Trees from 6-8 year sold to maturity are attacked. Larval damage also provides an avenue for infection by root-rotting fungi. This weevil may seriously hamper the establishment of pine plantations.

References and Links:

EAG: 554; FC: 326.

See Warren's Root Collar Weevil Stand Establishment Decision Aid.

Additional Images:

White crystallized resin indicates larval feeding. Young lodgepole pine killed by H. warreni.