ADULTS: in Eucnemidae antennomere 2 is attached subterminally to the scape (vs apically in Elateridae)
LARVAE- Often referred to as cross-grain borers. Four larval forms exist:
Buprestiform -- Larvae less sclerotized, often whitish, with expanded prothorax, much like in Buprestidae. These larvae will also have extremely small mandibles with outwardly projecting teeth. Some larvae will have some velvety patches on the surface of the segments and also will have elaborately shaped scleromes on the prothorax in the shape of a "T" or an inverted "L".
Elateriform -- heavily sclerotized, usually yellow-brown, wire-like and similar to elaterid larvae. head highly modified. These larvae will have lateral teeth on the outside edge of the head capsule. Their mandibles are extremely small with outwardly projecting teeth. The surface of each segment will be covered with velvety patches called microtricial patches.
Fusiform: usually not heavily armored, often whitish, with well expanded segments, similar to hymenopteran or dipteran larvae. Head capsules are either simplified and fleshy or armed with four to six anteriorally projecting teeth. Mandibles are not present, but possess a buccal region with labial and maxillary palpi. Larval types are primarily found in the tropics, but in case of the Nearctic region, may be present in two possibly three pantropical genera.
Onisciform: heavily sclerotized, generally flatter, with segments wider than long.
Range
worldwide, most diverse in the tropical/subtropical regions
Habitat
woodlands/forests, especially with a diverse structure, adults in tree canopy and on/under bark, larvae in moist dead wood, hard seasoned wood or in soil near roots of dead/dying trees (usually with fungi present)
in s.US adults may be seen as early as March; in the Pacific Northwest, as early as April; in Upper Midwest, NE and lower sections of w.NA, since mid-May/early Jun
Food
Larvae may be feeding on fungal mycelia in wood(4)
Life Cycle
Some species undergo a hypermetamorphic lifecycle, with a first instar being a free-living non-parasitic triungulin. It will molt into a completely different larval form later on. Some fifth instar larvae will transition into a prepupal stage, before entering the pupal stage.
Some eucnemid larvae, espcially those similar to elaterid larvae have been observed to bore along the grain of the wood. Other larvae (buprestiform), on the other hand have been known to cut across the grain; these are usually found in the sapwood within 2‒3" from the surface.
Most Nearctic eucnemids overwinter as larvae and continue development in the following spring. Many species complete development in 1‒2[3] yrs. Pupal cells are constructed near the surface and larvae have been seen in a u-shaped position.
Remarks
The term false click beetle is a misnomer, many eucnemids can click. ―Robert Otto, 3.v.2008
see (6)(7)(8) for new records not yet reflected in the Guide
Works Cited
1.
Family-group names in Coleoptera (Insecta) Bouchard P, Bousquet Y, Davies A, Alonso-Zarazaga M, Lawrence JF, Lyal CH, Newton A, Reid CA, Schmitt M, Ślipiński SA, Smith A. 2011. ZooKeys 88: 1–972.
