British insects: the families of Coleoptera
British insects: the families of Coleoptera |
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= Horiidae, including Tetraonychidae.
Oil Beetles, Blister-beetles.
General appearance. 7–32 mm long. Body length/maximum body width 1.1–7. Elytral length/pronotal length 0.4–5.4. Base of prothorax not or scarcely narrower than the combined elytral bases, or distinctly narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width, or distinctly narrower than greatest elytral width. Beetles oval to elongate; abruptly conspicuously necked; somewhat waisted to conspicuously waisted (expanded at the distal part of the abdomen, rather than waisted); reddish yellow, or greenish-, violet- or bluish-black; exhibiting bright ‘warning colours’, or without ‘warning colouration’. Upper surfaces of body glabrous or subglabrous, or non-glabrous; exhibiting stiff, erect, dark bristles, or not bristly; with neither scales nor scale-like setae.
Detailed morphology. Beetles prognathous, or not prognathous. Inclination of the head slight to very strong. Eyes strongly protuberant, or not strongly protuberant; without bristles. Antennae short to about half the insect's head to tail length; 6–11 segmented. Antennal scape not swollen. Antennae filiform. Antennal insertions visible from above; not in fossae. Mandibular prosthecae well developed to absent. Prothorax shorter than wide. Pronotal length/maximum pronotal width 0.47–1.6. Prothorax at its widest markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Metaventrite without a transverse groove. Fore coxal cavites closed behind. Hind coxae not shaped posteriorly to receive the femur. Tarsal segmentation formula 5, 5, 4. The tarsi without bilobed segments; without ‘hidden’ segments. Front tarsi with as many segments as the mid-tarsi; 5-segmented. Mid-leg tarsi 5-segmented; pentamerous. The claws of the mid-leg tarsi with an appendage, or not appendaged; appendages when present, not or only lightly sclerotized, or heavily sclerotized, blade-like, or heavily sclerotized, spine-like or bristle-like. The claws of the mid-leg tarsi simple, or one-toothed or bifid, or serrate, denticulate or pectinate (often with a sclerotized, blade-like process beneath each claw); with an empodium between them (this with no more than two setae), or without an associated empodium. Hind tarsi with one segment fewer than the mid-tarsi; 4-segmented. Elytral length/maximum width across the elytra 0.35–3.3. Elytra individually distinctly tapered to their apices to not individually tapered; not meeting along the full length of the mid-line (their apices well separated); covering most to all of the abdomen, or short, exposing several terminal abdominal tergites (often); exposing no more than part of the terminal tergite to at least three complete abdominal tergites; not truncate; soft. Scutellary striole absent. Wings well developed, or absent or much reduced. Exposed abdominal sternites 5–7; all articulated and movable. Abdominal segment 8 apparently without functional spiracles.
Adult habitat, ecology. Not predacious; phytophagous; in living vegetation.
Larvae. Larvae predacious; in bees' nests, eating eggs, honey and pollen stores. The larvae are heteromorpic (cf. Rhipophoridae), with the first instar triangulin, the second caraboid, the third and fourth scarabaeoid, the fifth coarctate and the sixth scolytoid.
Classification. Suborder Polyphaga; Infraorder Cucujiformia; Superfamily Tenebrionoidea.
Worldwide and British representation. About 7500 species worldwide; genera about 120. 9 species in Britain; genera in Britain 3; Apalus, Lytta, Meloë. E.g., M. brevicollis (Short-necked Oil-beetle); A. muralis (Bees'-nest Beetle).
General comments. Moderate-sized beetles with rather soft integument, with some overseas species having maxillae are adapted for absorbing nectar. Secretors of the defensive blistering agent, cantharidin.
Illustrations. • Lytta vesicatoria: B. Ent. 658. • Lytta vesicatoria: B. Ent. 658, legend+text. • Lytta vesicatoria: B. Ent. 658, text cont.. • Lytta vesicatoria (Janson 159). • Meloë brevicollis (Short-necked Oil-beetle): B. Ent. 279. • Meloë brevicollis: B. Ent. 279, legend+text. • Meloë brevicollis: B. Ent. 279, text cont.. • Meloë violacea (Oil-beetle: Giles Watson, photos). • Meloë violacea (Oil-beetle, female depositing eggs: Giles Watson, photos). • Apulus muralis (Bees’-nest beetle: B. Ent. 340). • Apulus muralis (details, B. Ent. 340). • Apulus muralis: B. Ent. 340, legend+text. • Apulus muralis: B. Ent. 340, text cont.. • Apalus muralis (as Sitaris), Lytta vesicatoria, Meloë 6 spp. (with Aderidae and Anthicus): Fowler 5, 151 (1891). • Fowler 5, 151 (1891): original legend.. • Apulus muralis, with unrelated taxa: Fowler Suppl. 19, 1913. • Fowler Suppl. 19, 1913: original legend.
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the families of Coleoptera. Version: 2nd January 2012. http://delta-intkey.com’.
