Western conifer seed bug
Encyclopedia
The western conifer seed bug, Leptoglossus occidentalis, sometimes abbreviated as WCSB, is a species of true bug
(Heteroptera) in the family
Coreidae
. It was originally native to the warm-temperate
western USA (California
, Oregon
and Nevada
) but has in recent times expanded its range and become an invasive species
in parts of Europe
.
This species
is sometimes colloquially called "the leaf-footed bug", but actual leaf-footed bugs are an entire group of species in Leptoglossus
and related genera
of the Coreidae; see for example the Florida leaf-footed bug
, L. phyllopus.
Western conifer seed bugs are sometimes mistakenly identified as stink bugs due to the unpleasant aroma they emit when disturbed.
(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 spray a bitter, offending smell, though sometimes they can smell pleasantly of apples or pine sap; 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 poison.
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 seed
s to wither and misdevelop. It is therefore considered a minor tree pest in North America
, but becoming sometimes more harmful e.g. in conifer plantation
s. However, it is not monophagous and even adaptable enough to feed on angiosperms if it has to, though it seems to prefer resin
iferous plants that are rich in terpene
s. As these are produced by plants to deter herbivore
s, 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 nymph
ae 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.
and has steadily expanded eastwards. On its native continent, L. occidentalis has been located as far northeast as Maine
.
A popular nickname given to the bug in Ohio
is the walky bug, due to the slow and steady way it walks. It has also been known as the flick bug, from the method some people use for removing an annoying individual.
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
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 Oostende (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. During the autumn of 2008, a large influx of this species arrived on the south coast of England, indicating natural immigration from continental Europe. In late 2009, a large group of western conifer seed bug invaded Koç University in Istanbul, Turkey.
It was also first recorded from Tokyo
, Japan
in 2008, and some additional records from Tokyo and Kanagawa Prefecture
have been added until 2009.
Heteroptera
Heteroptera is a group of about 40,000 species of insects in the Hemiptera. Sometimes called "true bugs", that name more commonly refers to Hemiptera as a whole, and "typical bugs" might be used as a more unequivocal alternative since among the Hemiptera the heteropterans are most consistently and...
(Heteroptera) in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Coreidae
Coreidae
Coreidae are a large family of predominantly herbivorous insects that belong in the hemipteran suborder Heteroptera. There are more than 1,800 species in over 250 genera. They vary in size from 7 to 45 mm, making the larger species some of the biggest heteropterans. The body shape of coreids...
. It was originally native to the warm-temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
western USA (California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
and Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
) but has in recent times expanded its range and become an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
in parts of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
This species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is sometimes colloquially called "the leaf-footed bug", but actual leaf-footed bugs are an entire group of species in Leptoglossus
Leptoglossus
Leptoglossus is a genus of true bugs in the leaf-footed bug family. Several species are economic pests of agricultural crops. Like members of some other genera in the family, these bugs have leaflike dilations of the hind tibia.Species include:...
and related genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
of the Coreidae; see for example the Florida leaf-footed bug
Florida leaf-footed bug
The Florida leaf-footed bug is a species of insect. The genus name Acanthocephala means spiny head and was so-named from the pointed tylus at the tip of the head of this leaf-footed bug....
, L. phyllopus.
Western conifer seed bugs are sometimes mistakenly identified as stink bugs due to the unpleasant aroma they emit when disturbed.
Description
The average length is 16-20 millimeters, 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 bugWheel bug
The wheel bug , in the family Reduviidae, is one of the largest terrestrial true bugs in North America, being up to 1.5 inches, or 38 mm, in length; it is the only member of its genus. A characteristic structure is the wheel-shaped pronotal armor...
(Arilus cristatus) and other Reduviidae (assassin bugs). These, being Cimicomorpha
Cimicomorpha
Cimicomorpha is an infraorder of insects containing bugs....
, are not very closely related to leaf-footed bugs as Heteroptera
Heteroptera
Heteroptera is a group of about 40,000 species of insects in the Hemiptera. Sometimes called "true bugs", that name more commonly refers to Hemiptera as a whole, and "typical bugs" might be used as a more unequivocal alternative since among the Hemiptera the heteropterans are most consistently and...
go; though both have a proboscis
Proboscis
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:...
, but only the assassin bugs bite
Insect bite
Insect bites and stings occur when an insect is agitated and seeks to defend itself through its natural defense mechanisms, or when an insect seeks to feed off the bitten person. Some insects inject formic acid, which can cause an immediate skin reaction often resulting in redness and swelling in...
even if unprovoked, and L. occidentalis like its closest relatives can be most easily recognized by the expanded hindleg tibiae
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
and by the alternating light and dark bands which run along the outer wing edges on the flaring sides of the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. Their primary defense is to spray a bitter, offending smell, though sometimes they can smell pleasantly of apples or pine sap; however, if handled roughly they will stab with their proboscis, though they are hardly able to cause injury to humans as it is adapted
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
only to suck plant sap and not, as in the assassin bugs, to inject poison.
Ecology
Plant sap
Sap is a fluid transported in xylem cells or phloem sieve tube elements of a plant. It transports water and nutrients throughout the plant....
of developing conifer cones throughout its life, and its sap-sucking causes the developing seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s to wither and misdevelop. It is therefore considered a minor tree pest in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, but becoming sometimes more harmful e.g. in conifer plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...
s. However, it is not monophagous and even adaptable enough to feed on angiosperms if it has to, though it seems to prefer resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
iferous plants that are rich in terpene
Terpene
Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...
s. As these are produced by plants to deter herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, 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
Lodgepole Pine
Lodgepole Pine, Pinus contorta, also known as Shore Pine, is a common tree in western North America. Like all pines, it is evergreen.-Subspecies:...
(Pinus contorta), the White Spruce
White Spruce
Picea glauca is a species of spruce native to boreal forests in the north of North America, from central Alaska east to Newfoundland, and south to northern Montana, Minnesota, Wisconsin, Michigan, upstate New York, Vermont, New Hampshire, and Maine; there is also an isolated population in the...
(P. glauca), and the Coast and Rocky Mountain Douglas-firs
Coast Douglas-fir
Pseudotsuga menziesii, known as Douglas-fir, Oregon Pine, or Douglas spruce, is an evergreen conifer species native to western North America. Its variety Pseudotsuga menziesii var. menziesii, also known as coast Douglas-fir grows in the coastal regions, from west-central British Columbia, Canada...
(Pseudotsuga menziesii). Outside the native range it is also found on species like the Eastern White Pine
Eastern White Pine
Pinus strobus, commonly known as the eastern white pine, is a large pine native to eastern North America, occurring from Newfoundland west to Minnesota and southeastern Manitoba, and south along the Appalachian Mountains to the northern edge of Georgia.It is occasionally known as simply white pine,...
(P. strobus) and Red Pine
Red Pine
Pinus resinosa, commonly known as the red pine or Norway pine, is pine native to North America. The Red Pine occurs from Newfoundland west to Manitoba, and south to Pennsylvania, with several smaller, disjunct populations occurring in the Appalachian Mountains in Virginia and West Virginia, as well...
(P. resinosa) in eastern North America and Europe, and the Mountain Pine
Mountain Pine
Pinus mugo, the Mountain Pine or Mugo Pine, is a high-altitude European pine, found in the Pyrenees, Alps, Erzgebirge, Carpathians, northern Apennines and Balkan Peninsula mountains from 1,000 m to 2,200 m, occasionally as low as 200 m in the north of the range in Germany and Poland, and as high...
(P. mugo), European Black Pine
European Black Pine
Pinus nigra, the European Black Pine, is a moderately variable species of pine, occurring across southern Mediterranean Europe from Spain to the Crimea, in Asia Minor and on Cyprus, and in the high mountains of the Maghreb in North Africa....
(P. nigra), Scots Pine
Scots Pine
Pinus sylvestris, commonly known as the Scots Pine, is a species of pine native to Europe and Asia, ranging from Scotland, Ireland and Portugal in the west, east to eastern Siberia, south to the Caucasus Mountains, and as far north as well inside the Arctic Circle in Scandinavia...
(P. sylvestris) and Pistachio
Pistachio
The pistachio, Pistacia vera in the Anacardiaceae family, is a small tree originally from Persia , which now can also be found in regions of Syria, Lebanon, Turkey, Greece, Kyrgyzstan, Turkmenistan, India, Pakistan, Egypt, Sicily and possibly Afghanistan , as well as in the United States,...
(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 nymph
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
ae go through 5 instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
stages before moulting
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
into adults. In the USA the species is univoltine, but in southern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
it completes two generations a year, and in tropical Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
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.
Range and invasiveness
This insect is common in its native range along the temperate and warmer regions of the Pacific coast of North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and has steadily expanded eastwards. On its native continent, L. occidentalis has been located as far northeast as Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
.
A popular nickname given to the bug in Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
is the walky bug, due to the slow and steady way it walks. It has also been known as the flick bug, from the method some people use for removing an annoying individual.
In Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
this species was first reported in 1999 from northern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
; it had probably been accidentally imported with timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
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
Balkans
The Balkans is a geopolitical and cultural region of southeastern Europe...
(Slovenia
Slovenia
Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...
and Croatia
Croatia
Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...
), the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
(Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
), and parts of the Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
; in 2003 it was found to occur in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
though this population probably derives from a separate introduction. The 2007 records from Weymouth College
Weymouth College
Weymouth College is a Further Education college located in Weymouth, England.The college has over 7,000 students, studying on a wide range of practical and academic courses in many different subjects...
(England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
) and Oostende (Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
) might also represent one or two further independent introductions. In late 2007, it was found at Wrocław and Miechów
Miechów
Miechów is a town in Poland, in Lesser Poland Voivodeship, about 40 km north of Kraków. It is the capital of Miechów County. Population is 11,852 ....
(Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
); these animals probably represent a further range expansion out of the Czech Republic. During the autumn of 2008, a large influx of this species arrived on the south coast of England, indicating natural immigration from continental Europe. In late 2009, a large group of western conifer seed bug invaded Koç University in Istanbul, Turkey.
It was also first recorded from Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
in 2008, and some additional records from Tokyo and Kanagawa Prefecture
Kanagawa Prefecture
is a prefecture located in the southern Kantō region of Japan. The capital is Yokohama. Kanagawa is part of the Greater Tokyo Area.-History:The prefecture has some archaeological sites going back to the Jōmon period...
have been added until 2009.