Maritime Earwig

Anisolabis maritima

We taped seven courtships and three copulations. Females were aggressive toward males in the preliminary stages of courtship, hitting them frequently with their cerci. In contrast to Carcinophora (below), males responded aggressively and frequently pinched females. A receptive female became gradually less aggressive, and the male oriented his cerci toward her and tapped her gently on the tip of her abdomen with the ventral surfaces of his cerci, also giving her brief pinches with the tips of his cerci (Figure 91). The male attempted intromission by twisting the tip of his abdomen 180° and pushing gently until their genitalia were in contact (Figure 91). Some courtships were short, with only a few taps by the male's cerci before intromission. During copulation the male moved his cerci gently from side to side and occasionally vibrated his antennae.

10, 11. Carcinophora robusta and C. americana

We taped 14 and 3 courtships, and 7 and 1 copulations respectively. No differences were noted between the species. Females pinched courting males on various occasions, but, when receptive, they became less aggressive and sometimes later in the interaction nibbled at the cerci of the male as he opened and closed them. The male did not respond aggressively to attacks from females, rather he repeatedly twisted the tip of his abdomen and gently tapped and rubbed against the female's abdomen and cerci with the ventral surfaces of the tip of his abdomen and the basal portions of his cerci (Figure 92). The male attempted to copulate by rubbing and pushing repeatedly with the ventral surface of his cerci against the genitalia of the female (Figure 93).

Anisolabis maritima (Bonelli)

Forficula maritima Bonelli in Géné, 1832, p. 224 [Mediterranean Region].

Anisolabis maritima (Bonelli), Burr, 1911b, p. 29. Rehn and Hebard (1917), p. 638.

This species is not represented in the present collection, but is recorded from Dominica by Rehn and Hebard (1917) without exact locality. The species is widely distributed in the West Indies, in both the Greater and Lesser Antilles.

LENGTH.—Body 15–18 mm., forceps 3–3.5 mm (males), 2.5–3 mm (females). Shining black; antennae brown; legs yellowish or brown, usually unicolorous; cuticle almost impunctate, very sparsely and weakly punctured on some abdominal tergites. Head broad, eyes small, pronotum large and transverse, widened posteriorly; abdomen widened medially and depressed. Each branch of male forceps trigonal at base, cylindrical distally, strongly curved, branches asymmetrical; those of female with branches closer together, and almost straight except for curved apices.

WORLD DISTRIBUTION.—Cosmopolitan; found in all faunal Regions except Australasian; typically maritime, and occurs along seacoasts. It is, however, subtropical or tropical in distribution and does not extend into the temperate zones for any appreciable distance.

Borellia Burr, 1909, p. 325 [type-species: Anisolabis moesta Géné, by original designation] [generic name preoccupied by Borellia Rehn 1906, Orthoptera].

Euborellia Burr, 1910, p. 448 [new name for Borellia Burr 1909].

Mainly rather smaller earwigs, and more slender than Anisolabis; brown to black, shining. Originally the genus was erected for those species of the Carcinophorinae in which the elytra were represented by lateral flaps on the mesonotum, but Burr (1915) amended this to include those species in which the male genitalia have short and broad parameres. This amendment leads to the inclusion in this genus of four groups of species, based on the degree of development of the elytra, or the absence of the elytra, and the presence or absence of visible wings.

1. Elytra entirely absent (Figure 9).

2. Elytra rudimentary, represented by lateral flaps on the mesonotum (Figure 10).

3. Elytra larger, and meeting along sutures; wings absent or concealed (Figure 11).

4. Elytra normally developed, and wings visible (as Figure 8).

The last group are almost entirely Old World in distribution, but the African Euborellia cinticollis (Gerstaecker), recorded from the Nearctic Region (Gurney, 1950) as an adventive, appears to be variable in the development of the elytra, and may belong to either groups 3 or 4 above. Recent studies, however, have suggested that more than one species may be represented in the present concept of E. cincticollis.

Distribution in all faunal Regions, but possibly mainly Oriental. One species, Euborellia annulipes (Lucas) is cosmopolitan in distribution, and has the widest distribution of all earwigs, while E. ståli (Dohrn) is almost circumtropical.

Two species are recorded from Dominica.

Anisolabis maritima Borelli

This species was found under rocks and logs that were in advanced stages of decomposition and in drains from houses where organic debris had accumulated.

The cerci of males and females are similar. Male cerci are somewhat more curved than those of the female, and the male pygidium is slightly wider (Figure 56).

We taped 12 high-level and 6 lower-level aggressive interactions. High-intensity interactions often occurred immediately following first contact. In open sites (petri dishes), antennal contact was followed by turning and striking or by curving the abdomen forward and then striking; only occasionally did a male strike directly backward. In contrast, in tunnels, where the animals were less mobile, males struck by first turning 180° and then moving directly backward.

Pinches were frequent in both situations. They lasted longer in tunnels than in the open. Pinches in the open usually occurred on the posterior portion of the abdomen (Figure 57), whereas those in tunnels occurred often on both the abdomen (Figure 58) and the thorax. Simultaneous pinches were rare. In three cases a male in the open lifted and shook a pinched opponent; in one case he then threw him against the wall of the dish (Figure 5). In some cases one male struck another with a lateral or a backward slam and knocked him some distance (Figures 59, 60).

When pinched, the opponent struggled to free himself by pulling, twisting his abdomen, returning the pinch, or biting the other male. Another tactic with which males freed themselves on several occasions was for the pinched male to turn and move forward under the abdomen of the other male, thus twisting the pinching male's abdomen sharply (Figure 61).

Low-intensity battles both in the open and in tunnels included presentations and short pushes with the cerci. Opponents were struck with the tip of the abdomen with the cerci spread. Winners of interactions in the open often swung their abdomens strongly from side to side after the opponent withdrew. Losers in tunnels were less likely to withdraw, rather they simply remained more or less immobile with their cerci toward the opponent.


10–12. Carcinophora rosenbergi Burr, C. americana Beauvois, and C. robusta Scudder

These species were found in and under rotten logs and rotting plantain trunks and also under stones.

In all three species male cerci are asymmetrical to varying degrees, and male cercus morphology is very similar to that of females (Figure 62 on page 37). We taped 7 high-level and 3 lower-level interactions in C. rosenbergi, 3 high- and 3 low-level interactions in C. americana, and 13 high- and 8 lower-level interactions in C. robusta. We were unable to discern differences in fighting behavior of males of these species, and thus we describe them together.

Most strikes in high-level interactions occurred immediately following first contact. Usually they occurred from a curved-abdomen position or as the animal turned (Figure 63). Pinches usually lasted several seconds and generally were on the opponent's abdomen (Figure 64) or, less often, farther forward (Figure 65). Sustained simultaneous pinches did not occur. Slams occasionally resulted in the opponent being knocked off his feet momentarily (Figure 63), but probably most slams included an attempt to pinch. On some occasions, the pinching animal eventually released his grip spontaneously. In others, the opponent seemed to break free by pulling, by slamming with his abdomen, by giving a return pinch with his cerci, or by twisting under the other male's body (Figure 64). In one case, a male C. robusta punctured his opponent's abdomen with a pinch, causing him to lose hemolymph.

Often strikes missed, apparently due to evasive movements by the opponent (Figure 66), and attackers sometimes responded to evasive actions by moving rapidly backward (Figure 67). Cerci also were held open during the strong side-to-side or dorsal swings of the abdomen that often followed a missed strike. Some of these swinging movements brought the cerci into contact with the other individual and were immediately followed by further attacks, suggesting that at least some swings were searching movements designed to reestablish contact with the opponent. Winners often chased losers with their cerci directed more or less anteriorly, a position from which further attacks were launched (Figure 67).

Some mid-level interactions involved hitting the opponent with the tip of the abdomen between the cerci while the cerci were held open. Missed strikes often were followed by strong side-to-side swings of the abdomen.

Low-level interactions involved presentation of cerci or, on one occasion, a series of mutual cercal taps while the cerci were held open.

Anisolabis maritima, commonly known as the maritime earwig or the seaside earwig, is a species of earwig in the family Anisolabididae. Similar to the seashore earwig, this species can be found near the shore line, and is cosmopolitan. It can be found in almost all biogeographic realms. Scientists believe that these earwigs originally came from Asia. Since then, however, they have been introduced to North America, and have now spread around the world due to international commerce.

This earwig is approximately 2.5 to 3 cm (1.0–1.2 in) long, and is a grayish or blackish in color with light yellow legs. Unlike many other species of earwigs, it does not have any wings. Male maritime earwigs are known for their characteristically asymmetrical forceps, which they use for mating, for capturing prey, and for protecting themselves. These forceps have even been known to be strong enough to break human skin.

This species preys on many different small invertebrates, including fleas, crickets, ants, small beetles, sowbugs; it even exhibits cannibalistic tendencies. Because of their location on the beach, maritime earwigs are often found under seaweed and driftwood during the day. They prefer “dark, warm, humid places” to stay in.

In maritime earwigs in particular, evidence of filial cannibalism has been found. Filial cannibalism is the practice of a mother eating some of her offspring. Scientists believe that maritime earwigs practice this behavior in order to make their clutch maintain the size that best optimizes their investment. In this case, the mother will often eat the youngest child, which serves to shorten the total time she spends caring for the young. As she optimizes the childbearing process, the amount of energy she has to spend on her remaining children increases, as does their chance of survival.