in 2005 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.
Range and invasiveness This insect is common in its native range along the temperate and warmer regions of the Pacific coast of North America and has steadily expanded eastwards. On its native continent,
L. occidentalis has been located as far northeast as
Nova Scotia. In Europe, this species was first reported in 1999 from
northern Italy; it had probably been accidentally imported with
timber and, as it seems, more than once, as its presence was subsequently reported from that country almost simultaneously from locations a considerable distance apart. By 2007, it had established itself in the northern
Balkans (
Slovenia,
Bosnia and Herzegovina, and
Croatia), the
Alps (
Austria,
Switzerland), and parts of the
Czech Republic,
France,
Germany and
Hungary; in 2003, it was found to occur in Spain, though this population probably derives from a separate introduction. The 2007 records from
Weymouth College (
England) and
Ostend (
Belgium) might also represent one or two further independent introductions. In late 2007, it was found at
Wrocław and
Miechów (
Poland); these animals probably represent a further range expansion out of the Czech Republic. In late 2009, a large group of western conifer seed bugs invaded
Koç University in
Istanbul, Turkey. The same thing happened in October 2012 in most of the cities of the French Alps, like
Moûtiers. In 2017 it appeared for the first time in the
Southern Hemisphere, with several records from
Chile. It was also first recorded from
Tokyo,
Japan in 2008, and some additional records from Tokyo and
Kanagawa Prefecture have been added until 2009. In 2010 the first detection was made in
Ukraine, in
Dniprorudne, On October 21, 2020, the first sighting in
Andorra was posted to
iNaturalist, On October 8, 2024, it observed in the mountains surrounding
Sofia,
Bulgaria, and again on October 20, 2024, in
Velingrad, which is a town surrounded by coniferous forest. In March 2025, it was observed in western
Romania. On September 29, 2025, it was observed in
Klaipėda,
Lithuania, near the port. ==References==