Western Conifer Seed Bug - Ecology

Ecology

In its native range the Western Conifer Seed Bug feeds on the sap of developing conifer cones throughout its life, and its sap-sucking causes the developing seeds to wither and misdevelop. It is therefore considered a minor tree pest in North America, but becoming sometimes more harmful e.g. in conifer plantations. However, it is not monophagous and even adaptable enough to feed on angiosperms if it has to, though it seems to prefer resiniferous plants that are rich in terpenes. As these are produced by plants to deter herbivores, it might be that in evolving its ability to overcome these defenses, L. occidentalis actually became somewhat dependent on such compounds.

Its host plants in the native range includes conifers like the Lodgepole Pine (Pinus contorta), the White Spruce (P. glauca), and the Coast and Rocky Mountain Douglas-firs (Pseudotsuga menziesii). Outside the native range it is also found on species like the Eastern White Pine (P. strobus) and Red Pine (P. resinosa) in eastern North America and Europe, and the Mountain Pine (P. mugo), European Black Pine (P. nigra), Scots Pine (P. sylvestris) and Pistachio (Pistacia vera) (pistaches or pistacio trees) in Europe.

The eggs are laid in small groups on the needles or leaf stems of its host plants, and hatch in spring. The nymphae go through 5 instar stages before moulting into adults. In the USA the species is univoltine, but in southern Europe it completes two generations a year, and in tropical Mexico even three. In the northern parts of its range, these bugs start to move about widely by September or so to seek crevices for overwintering; they may become a nuisance in areas with extensive conifer woods as they will sometimes enter houses in considerable numbers.