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Engraver beetles
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| Pine engraver damage |
| W. Ciesla |
Host: Pine species, particularly lodgepole and ponderosa pines.
Distribution: Throughout range of pine species.
Identification: Reddish-brown boring dust accumulating in bark crevices or on top of logs; distinctive galleries apparent under bark layer; fading crowns of standing trees.
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| Pine engraver boring dust |
| B. Steed |
Damage: Beetles feed in phloem under the bark and girdle the tree.
Ecology: Engraver beetles are secondary beetles and preferentially inhabit slash material (recent logging debris, windthrown trees, freshly cut firewood, damaged trees, etc.). However, significant damage can occur in stands after disturbance, such as weather events or logging activities, when beetles attack and kill standing trees. Outbreaks generally do not last for more than one year.
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| Adult pine engraver beetle |
| L. Livingston |
Life Cycle: Adult beetles overwinter in duff layer of forest floor and emerge in early spring to attack slash (recent logging debris, windthrown trees, freshly cut firewood, damaged trees, etc). Males attract multiple females and each constructs an egg gallery under the bark. Eggs hatch and larvae feed in radiating galleries, becoming adults in less than two months. This generation of adults emerge from under the bark and seek fresh slash material but if none is available, will attack small diameter trees or the tops of larger trees. There are two to three generations of engraver beetles in Montana, depending on temperature and precipitation.
Management
Prevention: Typically, slash produced between August and December dries over the course of the winter and does not contain adequate moisture to support engraver beetles. Restricting logging activities to this window of time may greatly reduce the potential for an outbreak.
Slash disposal: If slash must be produced during January through June, prompt removal or burning will eliminate the success of beetles inhabiting and reproducing in the stand.
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| Pine engraver galleries |
| S. Tunnock |
Green chaining: Because engraver beetles prefer slash over standing trees, it is possible to lure the second generation of beetles from one slash pile to another, freshly created pile. This is accomplished by continually creating slash piles throughout a stand of older, infested slash piles.
Slash piles: The exterior portion of large slash piles may dry out while the interior retains its moisture. Beetles emerging from the exterior will migrate in toward the moister material. Creating large slash piles will accommodate the second generation and will reduce attack to surrounding trees.
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| Pine engraver galleries |
| K. Gibson |
Traps: Pheromone-baited traps effectively lure beetles from slash piles and reduce the likelihood that they will attack surrounding trees. Traps must be placed before the second generation of beetles fly. Hang traps from non-host trees or at least four feet from host species. For more information on this tactic, please contact the DNRC Forest Pest Management Program coordinator.
Links |
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| Forest Insect and Disease Leaflet (FIDL) | Field Guide - Identification | Management Guide | ||
Additional Common Forest Insects in Montana
| Douglas-fir Beetle | Red Turpentine Beetle |
| Douglas-fir Tussock Moth | Spruce Beetle |
| Fir Engraver | Western Pine Beetle |
| Mountain Pine Beetle | Western Spruce Budworm |
| Engraver Beetles (Ips species) |
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