Conocephalus fuscus

Some authorities, following H. Radclyffe Roberts (1941),[7] hold that this species should be referred to as Conocephalus discolor (Thunberg, 1815). The debate hinges on whether the specific epithet used by Fabricius in the combination Locusta fusca should be regarded as preoccupied by the naming of a species by Pallas in 1773 as "GRYLLUS Locusta fuscus" (this species is now known as Arcyptera fusca). Coray & Lehmann (1998)[8] refute this on several grounds, most tellingly that Pallas and Fabricius are referring to two different nominal genera for which the name Locusta had been proposed - Pallas refers to Locusta Linnaeus, 1758 (type species the migratory locust), and Fabricius to Locusta Geoffroy, 1762 (type species the great green bush-cricket). The apparent homonymy is therefore to be disregarded[9] and C. fuscus is the correct valid name. There are, however, still abundant references to C. discolor in modern literature, as well as to C. fuscus.[10][11][3][12][13][14][15][16][17][18][2][19][20][21][22][23][24][25][26][27]

The body of bush-crickets is covered by a protective exoskeleton and is divided into three parts: the head, thorax, and abdomen. The topmost segment of the thorax, the pronotum, is shaped like a saddle and is primarily used for protection. Bush-crickets are also equipped with large hind legs for jumping and biting mouth parts for grip and protection. The phenotypic aspects that are characteristic to this family of insects are the antennae, which typically exceed the length of their body, and the straight sword shaped ovipositor that the females use for laying eggs.[4]

The body of C. fuscus is 16–22 millimetres (0.63–0.87 in) when it reaches maturity.[28] Its hind wings are longer than its forewings, and they both reach beyond the tip of the abdomen. A distinctive dorsal stripe runs down the thorax, covering its head and pronotum, which is 12–17 millimetres (0.47–0.67 in) long. Adults have a slender grass-green body, brown wings, brown ovipositor, a reddish-brown abdomen, and a dark-brown stripe that edges white near the thorax. Nymphs differ slightly in colouration with a light-green body and a white-margined black stripe.[6]

C. fuscus is a wing polymorphic species. Most wing-dimorphic tettigoniids have a brachypterous (short-winged) form and a macropterous (long-winged) form. However, since C. fuscus is already considered a long winged species, its alternative form is extra long winged, with wing lengths up to a third longer than normal individuals.[29] An experiment performed by Ando and Hartley in 1982 on the embryonic development of this species provided evidence that the tendency for an individual to develop as one wing morph or the other is dependent on the density of the population. In this species the development of individuals with extra long wings is induced by crowding.

Wing dimorphism does not only affect wing length, but also affects flight, dispersal, and reproductive capability of this species. The juvenile hormone is responsible for wing polymorphism in orthoptera and has also been known to play a role in the trade-off between wing morphology and reproductive capability.[30]

C. fuscus can be found in parts of France, Italy, and the Netherlands, but it has made is biggest appearance in the United Kingdom. When the species was first discovered in Britain in the 1940s it was confined to the South Coast[3] but in the 1980s there was dramatic population growth and its range expanded more than 150 miles in 20 years.[31] Today the long-winged conehead can be found in northwestern parts of the country beyond the River Thames and as far west as Wales.[32]

The increase in the global climate over the past few decades has had a significant impact on the spread of this species. The northward range expansion coincides with the worldwide increase in temperature due to the greenhouse effect.[32] Universally, species respond to fluctuations in climate by increasing or contracting their breeding ranges. If the opportunity arises for a species to expand its realised niche due to favourable conditions that have become available, it is advantageous for them to do so. In the 1950s the climate began to cool in the northern hemisphere, causing longer winters in southern Europe. This kept the long-winged coneheads in the southern part of the UK, where they were first sited, for a period of time.[32] In 1975 the effects of the greenhouse gases began to neutralise the cooling effects from the previous decades, and as the climate in the United Kingdom slowly rose, the long-winged coneheads started to increase the limits of their range farther northward. However, the major expansion did not occur until 1980 when global warming caused a significant increase in temperature in the northern hemisphere.[32] Since 1980 the temperature has risen linearly by 0.13 °C or 0.23 °F ± 0.03 °C or 0.05 °F per decade and the greatest impact fell between 40°N and 70°N latitude. This latitudinal region includes the United Kingdom and southern Europe, which explains why the long-wing conehead, and other European fauna, has responded most readily to the warming climate and expanded its range.

Another factor propagating this expansion is the presence of extra long-winged individuals within the species. The populations found farther north, at the range borders, have a higher percentage of extra long-winged (macropterous) individuals in comparison to populations in range core. Ando and Hartley (1982) found the macropters to be more active and capable of sustained flight. The long-winged individuals would engage flight for short periods of time if disturbed but would more readily seek cover. Simmons and Thomas (2004) also found that there was a difference in flight capability between the range populations. Individuals in border populations were able to fly up to four times longer (16.7 km or 10.4 mi ± 2.3 km or 1.4 mi) than those in the core (4.2 km or 2.6 mi ± 0.8 km or 0.50 mi). This suggests that there may be genetic differences between the two range populations and that the effect density on the formation of one phenotype or another is a plastic response; however, this evidence is not definitive. It is clear that macropterous individuals have a selective advantage due to their capability for sustained flight,[30] allowing them to form new colonies and benefit from habitats that have opened up farther north.

This expansion is beneficial for the species as well as the individuals within the species. As the species expands its range as a whole the individuals can take advantage of the unclaimed territory, which previously had an unsuitable climate. The individuals that now inhabit the area do not have to compete for resources such as food and shelter, and therefore can put more time and energy into ensuring the reproductive success of their offspring and the prorogation of their own genes.[33] This is especially beneficial for the extra long-winged individuals who experience a reproductive trade off with wing morphology.[30]

Conocephalus fuscus shares the same habitat as many species of bush-crickets. It makes its home in grassy meadows, woodlands, dry heaths, and among course vegetation. They can also be found living near water in reed beds, marshes, or bogs.[4] This species prefers areas with a warm climate, as evident by their recent northern dispersal due to the increase in global climate.[32]

This species is omnivorous, though its diet is mostly vegetarian. The long-winged conehead feeds primarily on grasses as well as small invertebrates such as aphids and caterpillars.[5]

Conocephalus fuscus is active during the day, and their main form of locomotion is walking. However, they use their large hind legs for jumping when under threat of predation.[28]