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Hosts

Plants with clasping leaf sheathes, such as, Canna spp. Cordyline spp. (ti), Dracaenaspp., Freycinetia spp. floral ginger, Heliconia spp., sugarcane (Zimmerman 1948).

Distribution

The black earwig was found in the Hawaiian Islands by early voyagers. It has a wide distribution in the Pacific. Originating in the Orient, it is one of the most common earwigs in Hawaii, preferring the wetter areas of the Islands (Zimmerman, 1948). It is found on all six major Islands (Hawaiian Terrestrial Arthropod Checklist ,1992).

Damage

Although black earwigs have been observed feeding on fruits of a native screw pine, examination of digestive systems shows that it prefers an insect diet. It has been observed feeding on caterpillars and leafhoppers (Terry, 1905). For this reason it can be seen as beneficial, except for two problems. It hitchhikes on exported commodities, causing quarantine concern. and its frasse and other metabolic waste products may soil or even damage flowers.

Biology

EGGS

Eggs are laid in masses in the leaf sheaths of large-leafed plants, such as Canna and sugarcane. The batches of 40 to 60 white, oval eggs measuring 1 mm x 0.75 mm are guarded by the mother during incubation. If she is disturbed, however, she may eat the eggs. During the 6 day incubation period eggs nearly double in size, and the embryo becomes clearly visible (Terry 1905).

LARVAE

There are several molts after hatching. The larval instars don't change in general appearance except to become darker and larger, to develop wings, and to have progressively longer antennae due to addition of segments. Larval development lasts about 50 days (Terry 1905).

ADULT

The black earwig is up to 36 mm (1.5 in) long, shiny black, with long, beaded antennae and a pincers or forceps on the hind end (Terry, 1905).

Behavior

Black earwigs are active at all times of the day, running over leaves in search of food.

Adults can unfold their wings rapidly and fly away It prefers wet habitats to dry ones (Terry, 1905).

Management

NON-CHEMICAL CONTROL

As a carnivore, this insect is beneficial and needs no control. If populations are high enough to soil cut flower commodities or cause quarantine concern, field or post harvest control may be necessary. Immersion in water repels them, and hot water immersion easily kills them.

CHEMICAL CONTROL

Insecticide dips repel or kill earwigs. Field insecticides lower populations.

References

Burr, Malcolm. 1910. Dermaptera. In: Fauna of British India. Taylor and Francis: London. i-xviii, 1-217, figs. 1-16, pls. 1-10.

Hawaiian Terrestrial Arthropod Checklist. 1993. Gordon M. Nishida, Ed. Bishop Museum: Honolulu, Hawaii, 262 pp.

Terry, T. W. 1905. Leafhoppers and their natural enemies, part 5, Forficulidae. Hawaiian Sugar Planters' Association Expt. Station. Div. Ent. Bull. 1(5): 163-174.

Zimmerman, E. C. 1948. Insects of Hawaii vol. 2: Apterygota to Thysanoptera. University of Hawaii Press: Honolulu. 475 pp.

NOV/1992

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