Anisolabis maritima

Invasion History

First Non-native North American Tidal Record: 1853
First Non-native West Coast Tidal Record: 1920
First Non-native East/Gulf Coast Tidal Record: 1853

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General Invasion History:

Anisolabis maritima, (Seaside Earwig) was first described from the Mediterranean (Italy) in 1832 (Scudder 1876a; Langston 1974). Its native region is somewhat uncertain because this species was probably transported widely by shipping before its description (Hincks 1947). The Mediterranean region, from which it was described, seems a likely choice (Carlton 1979; Cohen and Carlton 1995). It was subsequently found widely distributed in temperate to tropical coastal habitats (Scudder 1876a), on all continents and many islands, including the West Indies (Rehn and Hebard 1917), Mauritius (Hincks 1947), Hawaii (Carlton and Eldredge 2009), the Canary Islands, and New Zealand (Langston 1974). This insect, because of its preference for shoreline debris, has high potential for transport by shipping (Carlton 1979) and has probably been transported by humans over most of its present range (Scudder 1876a; Hincks 1947).  This earwig is often abundant in crevices in marinas and docks, and can occur on small boats and ships (Fofonoff, personal observations).

North American Invasion History:

Invasion History on the West Coast:

The Seaside Earwig (Anisolabis maritima) was collected on Vacouver Island in 1920 (Vickery and Kevan 1985), San Francisco Bay in 1933 (Cohen and Carlton 1995), and Laguna Beach, southern California by 1922. This insect's distribution on the Pacific Coast of North America appears to be spotty, rather than continuous (Carlton 1979; Cohen and Carlton 1995; GBIF 2022). This insect was probably introduced with dry ballast and cargo.

Invasion History on the East Coast:

Anisolabis maritima was first collected in North America in South Carolina in 1853 (Langston 1974). It has been considered to be most likely introduced (Morse 1920; Scudder 1876b), though Scudder noted that 'This may be indigenous, but it occurs over nearly the whole world.' On the Atlantic coast, it was known from Key West (Florida) to North Carolina by 1876 (Scudder 1876b), and reported from the shore of Long Island Sound (Cold Spring Harbor, New York; Bennett 1904). Bennett considered these insects to be rare in New England, but by 1924, they were known from Maine to Connecticut (Morse 1920). The fact that the early records of this species came from the southeast, suggests that this earwig may have extended its range northward, considering the high frequency of collectors in the Northeast. However, records of the Global Biodiversity Information Facility (GBIF 2023) indicates that likely this species has few records in the Carolinas, but many in the Atlantic Coast of Florida.  It was collected along the Indian River Lagoon (1896, Rehn and Hebard 1916). Likely vectors of introduction are dry ballast and cargo.  

 

Invasion History on the Gulf Coast:

Anisolabis maritima was reported on Key West by by Scudder (1876a) and found at several Florida Gulf coast sites, and in Galveston, Texas in 1910 (U.S. National Museum of Natural History Entomology Collections 2020).  Reported records in the Global Biodiversity Information Facility are spotty outside of the Gulf Coast of Florida (GBIF 2023).

 

Invasion History in Hawaii:

Kaalaea Beach, Oahu/HI/Pacific Ocean (1953, Brindle 1980); Oahu/HI/West Loch, Pearl Harbor (1974, Brindle 1980); Midway Atoll/Pacific Ocean; Laysan Island/HI/Pacific Ocean (1914, Fullaway 1914, cited by Brindle 1980)

Invasion History Elsewhere in the World:

Anisolabis maritima, (Seaside Earwig) was first described from the Mediterranean (Italy) in 1832 (Scudder 1876a; Langston 1974). Its native region is somewhat uncertain because this species was probably transported widely by shipping before its description (Hincks 1947). It has been introduced to the Azores, the Canary Islands, Bermuda, and the eastern Antilles  )Global Biodiversity Facility  2023).  In the Indo-Pacific, it is widespread in coastal China Korea, and Japan (Global Biodiversity Facility 2023), and from Mauritius, and New Zealand  (Hincks 1947).

In the Eastern Pacific, it is known from the Galapagos Islands (1905, Carlton et al. 2019), Cocos Island, Costa Rica, (Hogue and Miller 1981) and the Isla Secas Islands, Panama (GBIF 2023).

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Description

Anisolabis maritima is a large earwig, usually associated with the littoral zone of marine and estuarine habitats, often under logs and rocks and in wrack-piles along the upper tideline. It was described from the Mediterranean Sea and is now widespread on temperate and tropical shores. Adults are 16–26 mm long. Males have strongly curved forceps (‘pincers’ at the end of the abdomen) compared to females. Females are larger than males. The body is dark brown with yellowish legs (Bennett 1904: Blatchley 1920; Vickery and Kevan 1975).

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Taxonomy

Ecology

General:

In Europe, North America, and throughout most of its range, the Maritime Earwig tends to favor littoral habitats near the sea. It is often found on beaches and on the banks of rivers under pieces of timber and ‘rejectamenta of all kinds ' (Hincks 1947). On the shores of Vancouver Island, British Columbia, they were found 'in trash at the high-water level and well above this mark, and under the bark of logs on the shore' (Vickery and Kevan 1985). In California, 'Many of the areas where this earwig was found were rocky with considerable drift and debris, but very little noticeable plant life' (Langston 1974). However, in Maryland (Kent Island) it was collected from a brackish marsh, dominated by Spartina alterniflora (Smooth Cordgrass), Phragmites australis (Common Reed), and Iva frutescens (Marsh Elder) (Bickley and Seek 1975).  At temperatures near freezing, these insects retreat to sites well above the high-tide mark, where they become dormant. While A. maritima is most frequently found on marine and estuarine strandlines, it has also been collected from the shores of the St. Lawrence River near Montreal and Lake Ontario (Vickery and Kevan 1985), and in mountains in France, Burma, and Lebanon (Hincks 1947). Most reports are from the upper strandline of tidal shores. However, 'It is probable that A. maritima moves up and down from the high tide level to feed. (Langston 1974). 'When disturbed, they frequently enter the water' (Bennett 1904). 

 

Food:

amphipods, fly larvae, crickets, drowned insects

Consumers:

Competitors:

Trophic Status:

Carnivore

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Habitats

General Habitat	Coarse Woody Debris	None
General Habitat	Unstructured Bottom	None
General Habitat	Marinas & Docks	None
General Habitat	Rocky	None
Salinity Range	Oligohaline	0.5-5 PSU
Salinity Range	Mesohaline	5-18 PSU
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Mid Intertidal	None
Tidal Range	High Intertidal	None
Tidal Range	Supratidal	None
Tidal Range	Terrestrial	None
Vertical Habitat	Endobenthic	None
Vertical Habitat	Epibenthic	None

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Life History

Reproduction: Sexes are separate. Males tend to be larger than females. Fertilization is internal. Females dig burrows in sand or nest in crevices in rotten logs and lay the eggs there, later guarding the eggs and young (Vickery and Kevan 1985).

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Tolerances and Life History Parameters

Minimum Salinity (‰)	0	Tolerates seasonal exposure to freshwater, but apparently rarely established in permanently freshwater habitats in San Francisco Bay (Langston 1974) and Chesapeake Bay (Fofonoff, personal observation)
Maximum Salinity (‰)	37	Typical Mediterranean salinity
Broad Temperature Range	None	Cold temperate-Tropical
Broad Salinity Range	None	Mesohaline-Euhaline

General Impacts

Economic impacts of Anisolabis maritima (Seaside Earwig) have not been noted. Most people find them unattractive, but economic impacts are likely insignificant.

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References

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