Biology ofhylurdrectonus araucariaeSchedl (Coleoptera, Scolytidae), a pest of hoop pine plantations in New Guinea

Hylurdrectonus araucariaeSchedl is a major pest in hoop pine (Araucaria cunninghamii) plantations at Bulolo and Wau in Papua New Guinea, establishing itself in nests inside the branchlets. The length of the excavation is proportional to the age of the nest. Colour changes in infested branchlets reflect changes in colony composition and in excavation activity as the colony ages; the branchlet eventually dies and falls off and severely infested trees lose much of their foliage. Data from field observations between 1967 and 1972 show that there are 5–10 overlapping generations ofH. araucariaein a year. The life-cycle takes place wholly within the branchlet, except for a brief period of flight or walking by the adult when seeking new nesting sites. The eggs incubate for 5–15 days, larvae take 10–25 days, pupae 10–15 days, and the immature adult 2–10 days; the adult may live 60 days or more. The colony composition is fairly stable in heavily infested areas throughout the year, except during drought. Colony composition and size vary from branchlet to branchlet or from tree to tree, but are more similar on trees with a similar stage of infestation. No significant natural enemies were found.