Western Conifer Seed Bug (lat. Leptoglossus occidentalis)

The average length is 16–20 millimetres (0.63–0.79 in) with males being smaller than females. They are able to fly, making a buzzing noise when airborne. Western conifer seed bugs are somewhat similar in appearance to the wheel bug Arilus cristatus and other Reduviidae (assassin bugs). These, being Cimicomorpha, are not very closely related to leaf-footed bugs as Heteroptera go; though both have a proboscis, but only the assassin bugs bite even if unprovoked, and L.

occidentalis like its closest relatives can be most easily recognized by the expanded hindleg tibiae and by the alternating light and dark bands which run along the outer wing edges on the flaring sides of the abdomen. Their primary defense is to emit an unpleasant-smelling alarm pheromone; however, if handled roughly they will stab with their proboscis, though they are hardly able to cause injury to humans as it is adapted only to suck plant sap

and not, as in the assassin bugs, to inject venom.

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 include conifers such as Douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), and white spruce (Picea glauca). Outside the native range, it is found on species such as eastern white pine

(P. strobus) and red pine (P. resinosa) in eastern North America and Europe, and mountain pine (P. mugo), black pine (P. nigra), Scots pine (P. sylvestris) and pistachio (Pistacia vera) in Europe. The eggs are laid in small groups on the needles or leaf stems of its host plants, and hatch in spring. The nymphs go through 5 instar stages before moulting into adults. In the United States, 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. They have the potential to become structural pests, as it has been found that they will sometimes pierce PEX tubing

with their mouthparts, resulting in leakage.

This article draws heavily on the corresponding article in the Italian-language Wikipedia.

Stages of metamorphosis Status of L. occidentalis in Britain Pennsylvania State University - Western Conifer Seed Bug