|scientific name Scolytus |
common name Bark beetles
Bark beetles are commonly found on their host tree, as it is their breeding place and food source.
These beetles may overwinter as larvae or pupae, usually in the wood or bark of trees (Liu & Haack 2003, LaBonte et. al. 2003, Bright 1976). Adults generally emerge in spring or summer (Liu & Haack 2003, Bright 1976).
Scolytus sp. beetles are small, usually less than 5mm in length (Liu & Haack 2003, Bright 1976). Eyes are oval in shape and located on the sides of the heads behind the clubbed antennae. The antennae are clubbed and may have varying number of segments (usually 7) (Bright 1976). The flat elytra on these beetles are striated (with puncture holes) to a varying degree and always extend beyond the abdomen (Bright 1976). The ventral sternites of the abdomen, in turn, always ascend to meet the elytra (Bright 1976). Convexity of said sternites varies among species. Spines may also be present on the sternites, and the presence and location of these spines vary among species (Bright 1976, LaBonte et. al. 2003).
Females burrow into host trees and form parental galleries (sometimes with help from the males) into which eggs are laid (Liu & Haack 2003, Bright 1976). Larvae will initiate feeding upon hatch and feeding galleries extends at right angles from the parental gallery. Again, depending on the species, these feeding galleries may twist and turn, forming different species-specific patterns in the wood (Liu & Haack 2003, Bright 1976). Pupation occurs either in the wood or under the bark. Overwintering may be done in all stages of the life cycle (Liu & Haack 2003, Bright 1976). Adults may emerge throughout spring and summer, depending on whether conditions allow for multiple generations per year (Liu & Haack 2003, Bright 1976).
Larvae will feed on wood and adults target newly formed or dying twigs and limbs.
Scolytus beetles have a cosmopolitan distribution and species ranges have been changing constantly due to accidental introductions of beetles into new geographical ranges.
These beetles can be considered pests due to the amount of damages they may inflict on their host trees. In large numbers, larval feeding may girdle and kill trees while adult feeding may kill off entire branches (Liu & Haack 2003, Bright 1976). Furthermore, some species are capable of vectoring fungi that may be fatal to the trees, such as Ophiostoma ulmi, which is known for causing Dutch elm disease (Liu & Haack 2003, Bright 1976).
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