The Mediterranean pine engraver, Orthotomicus (Ips) erosus (Wollaston) (Coleoptera: Scolytidae), was first detected in May 2004 in North America in the central valley of California. Orthotomicus erosus is a pest of pines in the Mediterranean region, South Africa, and Chile and may also vector pathogenic fungi. In California, O. erosus has been found to naturally colonize and develop in Monterey, Aleppo, Brutia, Canary Island, Scots and Italian stone pine. In the laboratory from 2005-2006, we tested the reproductive ability of O. erosus, by introducing males and females into holes drilled in native and exotic pines, and non-pine conifers. Orthotomicus erosus reproduced on all tested native pines (eastern white, grey, jack, Jeffrey, loblolly, lodgepole, Monterey, pinyon, ponderosa, red, sugar), and exotic pines (Aleppo, Canary island, Italian stone, Scots). The beetle also reproduced on non-pine hosts such as Douglas-fir, black spruce and white spruce, and to a lesser degree, tamarack. Reproduction did not occur on coast redwood, white fir, and incense cedar. In 2007, we compared how naturally occurring O. erosus would colonize cut bolts placed in areas of high infestation, testing four native Californian pines (grey, Monterey, pinyon, ponderosa) and one exotic pine (Italian stone).