''Caconemobius fori'', the Kīlauea lava cricket or dark lava cricket (, ), is a species of lava

cricket Cricket is a Bat-and-ball games, bat-and-ball game played between two Sports team, teams of eleven players on a cricket field, field, at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cr ...

endemic to the island of

Hawai'i Hawaii ( ; ) is an island state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two non-contiguous U.S. states (along with Alaska), it is the only state not on the North American mainland, th ...

. It is found on recently solidified lava flows produced by

Kīlauea Kīlauea ( , ) is an active shield volcano in the Hawaiian Islands. It is located along the southeastern shore of Hawaii (island), Hawaii Island. The volcano is between 210,000 and 280,000 years old and grew above sea level about 100,000 years ...

and

Mauna Loa Mauna Loa (, ; ) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. Mauna Loa is Earth's largest active volcano by both mass and volume. It was historically considered to be the largest ...

Description

''Caconemobius fori'' is a small cricket, approximately in length.Gurney, A.B. & Rentz, D.C.F. (1978) The cavernicolous fauna of Hawaiian lava tubes. 10. Crickets (Orthoptera, Gryllidae). Pacific Insects, 18(1-2), 85–10

/ref> It lacks wings but is capable of jumping significant distances when disturbed. This species is darkly colored with an overall shiny quality, causing them to blend in extremely well with the freshly solidified lava that makes up their habitat. They have been noted to look very similar to the volcanic glass ejecta

Pele's tears Pele's tears (closest Hawaiian translation: "nā waimaka o Pele") are small pieces of solidified lava drops formed when airborne particles of molten material fuse into tearlike drops of volcanic glass. Pele's tears are jet black in color and a ...

which occur in their habitat.

Distribution and habitat

''Caconemobius fori'' is endemic to recently cooled (on the order of decades) lava flows on the big island of

. It is one of the first species to colonize a lava field after its formation, arriving even before any significant plant life can take hold. It is unknown where the crickets occur once a lava field has been colonized by plant life.Heinen-Kay, Justa & Rotenberry, John & Kay, Adam & Zuk, Marlene. (2021). Lava crickets ( Caconemobius spp.) on Hawai'i Island: first colonisers or persisters in extreme habitats?. Ecological Entomology. 46. 10.1111/een.13011. Once enough time has passed for any significant plant life to colonize a lava flow, ''C. fori'' disappears from the habitat. This species has never been recorded as occurring within 15m of any established vegetation. In contrast, it has been found as close as 100m from an active volcanic vent.

Ecology

''Caconemobius fori'' is a strictly

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

species. As ''C. fori'' is one of the first arrivals after a lava flow is formed, the species relies entirely on windblown debris for food, including plant material and

sea foam Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids) derived from sources s ...

. Nearly constant winds over fresh lava fields can carry debris multiple kilometers from its source, providing a source of nutrition for these crickets. While ''C. fori'' can be found at night on lava fields without any equipment, it is apparently especially attracted to

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, which is used by researchers to bait pitfall traps in order to study this species.

References

{{Taxonbar, from=Q10438979 Insects of Hawaii Ground crickets Insects described in 1978