Damaging Insects of Valley Pine

Rob Flowers, Entomologist, Oregon Department of Forestry

Since 2000, a number of insects have been observed causing damage to Valley ponderosa pine. The most severe damaging agents include pine engraver (Ips pini), California five-spined ips (I. paraconfusus), red turpentine beetle (Dendroctonus valens), mountain pine beetle (D. ponderosae) and sequoia pitch moth (Synanthedon sequoiae). Damage to new shoots resulted from fir coneworm (Dioryctria abietivorella) and Western pine spittlebug (Aphrophora permutata) feeding, while Ponderosa pine cone beetle (Conophthorus ponderosae) and deathwatch beetles (Ernobius spp.) damaged cones. Defoliation by pine sawfly larvae (Neodiprion spp.) has also been observed to occur periodically.

Photo by Bob Johnson (ODF, Veneta)
Bark beetles, including California five-spined ips (I. paraconfusus), have been the most significant damaging agents of Valley pine in recent years.

The majority of these agents appear infrequently and cause limited damage. However, localized outbreaks of Ips bark beetles (Figure 1) have caused significant mortality in young stands and top-kill in mature trees for several consecutive years. Beetle populations can build-up rapidly in early spring if abundant slash or storm blowdown / wind breakage is available, with subsequent generations attacking standing trees. Recent attacks killed several acres of young (3 dbh) Valley ponderosa pine in western Lane County (Figure 2). Often, it is difficult to assess the source of the population build-up, as beetles can fly to susceptible trees from up to a mile away. Therefore, it is essential to follow recommended guidelines on slash creation as well as communicate well with neighbors regarding plans for forest operations or the occurrence of storm damage. Restricting the availability of these materials will decrease the potential for damage to nearby stands.

Currently, there is rather limited information on the biology and ecology of Ips bark beetles in the Willamette Valley. Therefore, beginning in spring 2008, the ODF Forest Health Unit in cooperation with the US Forest Service has plans to begin trapping bark beetles at 15 sites along a North-South line through the approximate area that Valley ponderosa occurs. The native stand mapping project completed in 2002 will be used to locate traps, which will use general and species-specific lures. It is hoped that through this effort we will gain a better understanding of bark beetle distributions, abundance, flight periods and annual generations to assist in refining management strategies and reduce future damage.

Additional information on the biology and management of several of these damaging agents can be found on the ODF Forest Health website @ http://oregon.gov/ODF/PRIVATE_FORESTS/fh.shtml.


Last Updated 02/24/08