CURCULIONIDAE Latreille, 1802 

True Weevils

Beetles of this huge and highly diverse family occur on a very wide range of plant hosts in almost all terrestrial and wetland situations. The family includes some of our most common and widespread beetle species.

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POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

17

Approx. 170

Approx. 520

1-17.5mm

Introduction

The classification of this family is far from settled and many different versions will be found in the literature e.g. among the various UK checklists, but for the purpose of this site we follow the latest Palaearctic checklist and introduce the Brachycerinae, which includes several tribes variously defined as families or other groups i.e. Tanysphyrini, Raymondionymini and Erirhinini, but even without this broader definition it is among the most diverse families of organisms; with fewer species than the ichneumon wasps or the staphs, as recently and broadly defined, it is nonetheless the most diverse in a morphological sense. More than 60000 species and between 4000 and 5000 genera have been described worldwide. Diversity is greatest in warmer areas but most countries in temperate regions have a speciose fauna representing many subfamilies, among the most northerly of species is the arctic tundra weevil Isochnus arcticus (Korotyaev, 1976) (Curculioninae, Rhamphini), an arctic willow (Salix arctica Pall.) feeder which occurs to the far north of Greenland and Ellesmere Island, above 80° north. More than 2500 species have been recorded from the United States and 1500 from Europe, the U.K. fauna includes almost 500 species in about 165 genera and 14 or 15 subfamilies, although many of these are at the northernmost limit of their distribution and so are rare or localized to the south, and some are considered extinct for a variety of reasons but especially because of habitat alteration by humans. The majority of weevils are readily recognized by the rostrum, with the mouthparts mounted at the apex, geniculate antennae which are distinctly clubbed, and the bilobed third tarsomere. In some groups e.g. the Entiminae Schönherr, 1823, Cossoninae Schönherr, 1825 and Scolytinae the rostrum is broad and short or not recognizable as such, but these groups soon become familiar. Most species feed on plants or are saproxylic. The following list, adapted from the latest British checklist (Duff, 2016) as well as the Palaearctic list, will give some idea of the extent of the U.K. fauna:

  • BRACHYCERINAE Billberg, 1820

    • ERIRHININI Schönherr, 1825

    • TANYSPHYRINI Gistel, 1848

    • RAYMONDIONYMINI Reitter, 1913

  • BARIDINAE Schönherr, 1836

    • APOSTASIMERINI ​Schönherr, 1844

    • BARIDINI Schönherr, 1836

  • CURCULIONINAE Latreille, 1802

    • ACALYPTINI Thomson, C.G., 1859​

    • ANOPLINI Bedel, 1884

    • ANTHONOMINI Thomson, C.G., 1859

    • CIONINI Schönherr, 1825

    • CURCULIONINI Latreille, 1802

    • ELLESCINI Thomson, C.G., 1859

    • MECININI Gistel, 1848

    • RHAMPHINI Rafinesque, 1815

    • SMICRONYCHINI Seidlitz, 1891

    • STOREINI Lacordaire, 1863

    • STYPHLINI Jeckel, 1861

    • TYCHIINI Gistel, 1848

  • BAGOINAE Thomson, C.G., 1859

  • CEUTORHYNCHINAE Gistel, 1848

    • AMALINI Wagner, 1936

    • CEUTORHYNCHINI Gistel, 1848

    • MONONYCHINI LeConte, 1876

    • PHYTOBIINI Gistel, 1848

    • SCLEROPTERINI Schultze, 1902

  • COSSONINAE Schönherr, 1825

    • COSSONINI Schönherr, 1825

    • DRYOTRIBINI LeConte, 1876

    • ONYCHOLIPINI Wollaston, 1873

    • PENTARTHRINI Lacordaire, 1865

    • PROECINI Voss, 1956

    • RHYNCOLINI Gistel, 1848

  • CRYPTORHYNCHINAE Schönherr, 1825

    • CRYPTORHYNCHINI Schönherr, 1825​

  • CYCLOMINAE Schönherr, 1826

    • HIPPORHININI Lacordaire, 1863

  • DRYOPHTHORINAE Schönherr, 1825

    • DRYOPHTHORINI​ Schönherr, 1825​

    • RHYNCHOPHORINI Schönherr, 18238

  • ENTIMINAE Schönherr, 1823

    • ALOPHINI LeConte, 1874​

    • BRACHYDERINI Schönherr, 1826

    • CNEORHININI Lacordaire, 1863

    • GEONEMINI Gistel, 1848

    • OMIINI Shuckard, 1839

    • OTIORHYNCHINI Schönherr, 1826

    • PERITELINI Lacordaire, 1863

    • PHYLLOBIINI Schönherr, 1826

    • POLYDRUSINI Schönherr, 1823

    • SCIAPHILINI Sharp, 1891

    • SITONINI Gistel, 1848

    • TANYMECINI Lacordaire, 1863

    • TRACHYPHLOEINI Gistel, 1848

    • TROPIPHORINI Marseul, 1863

  • HYPERINAE Marseul, 1863

  • LIXINAE Schönherr, 1823

    • LIXINI Schönherr, 1823​

    • CLEONINI Schönherr, 1826

  • MESOPTILIINAE Lacordaire, 1863

    • MAGDALIDINI Pascoe, 1870​

  • MOLYTINAE Schönherr, 1823

    • HYLOBIINI Kirby, 1837

    • LEPYRINI Kirby, 1837

    • MOLYTINI Schönherr, 1823​

    • PHRYNIXINI Kuschel, 1964

    • PISSODINI Gistel, 1848

    • TRACHODINI Gistel, 1848

    • TYPODERINI Voss, 1965

  • OROBITIDINAE Thomson, C.G., 1859

  • SCOLYTINAE Latreille, 1804

    • HYLASTINI LeConte, 1876

    • HYLESININI Erichson, 1836

    • HYLURGINI Gistel, 1848

    • PHLOEOSININI Nüsslin, 1912

    • PHLOEOTRIBINI Chapuis, 1869

    • POLYGRAPHINI Chapuis, 1869

    • CORTHYLINI LeConte, 1876

    • CRYPHALINI Lindemann, 1876

    • CRYPTURGINI LeConte, 1876

    • DRYOCOETINI Lindemann, 1876

    • IPINI Bedel, 1888

    • SCOLYTINI Latreille, 1804

    • XYLEBORINI LeConte, 1876

    • XYLOTERINI LeConte, 1876

  •  PLATYPODINAE Shuckard, 1839

Description

Although most ‘weevils’ are readily recognized, species of Dryophthoridae, Erirhinidae and Raymondionymidae will conform to any general description because there is so much morphological overlap, but these families differ fundamentally in that the aedeagus is divided by a distinct lateral line into upper (tectum) and lower (pedon) parts, this pedotectal form is never seen in the ‘true’ weevils of the present family, and this difference is the basis for promoting the 3 former subfamilies to full families. Various other beetles also have a distinct rostrum e.g. some salpingids and mycterids (Tenebrionoidea), but they are always distinct in other ways.  Adult weevils vary from about 1mm to 40mm although the majority are between 2 and 20mm, the shape is very variable but generally elongate to very broadly oval, either continuous or discontinuous in outline and from strongly flattened to very convex, usually with the head, pronotum and elytra separately so. Colour varies very widely but the majority are rather drab, from black to testaceous, many are brightly coloured, sometimes brilliantly so, especially in tropical regions, and many are covered with recumbent or appressed scales which are often brightly coloured and metallic and form patterns, and fine pubescence, many are glabrous, or nearly so, or have erect or sub-erect setae. The form of the dorsal sculpture varies enormously but most are smoothly convex and lack major sculpture, especially those in temperate regions, but many exceptions occur, especially in the tropics where some truly striking examples of structural modification occur. The head is often proportionally small, generally prognathous and variously inserted into the prothorax so that some or all of the temples are concealed (many exceptions occur), with the eyes on the lateral margin or occupying much of the lateral and dorsal area. The eyes vary in size, shape and convexity and in some are reduced or absent. The rostrum varies from very short and broad, sometimes indistinct, to very long and narrow, in many it is curved downwards and sexually dimorphic; longer, narrower and with the antennae placed nearer the base in the female. In most cases there are lateral or dorso-lateral scrobes into which the antennae fold and which protects them when the weevil is boring into host material. Antennae often long and slender, usually geniculate with a 5-7 segmented funiculus and a distinct 1-3 segmented club. Mouthparts mounted at the rostral apex; mandibles short and broad, in some with a deciduous process or scar at the apex, labial palps 1 or 2 segmented, rarely absent but in some recessed into cavities on the ventral surface of the prementum, maxillae sometimes concealed by an apically expanded mentum, in some with distinct galea and lacinia. Pronotum extremely variable; widely transverse to very elongate although in most near-quadrate, and, in warmer regions, with a wide range of sculpture. Elytra equally variable, from flat to evenly convex, smooth or sculptured and shiny to heavily microsculptured or striate, in many scolytids the elytra are adapted to wood-boring, the apex is excavate and toothed along the lateral margin, modifications that help push against the side of the galleries and clear away wood dust and frass. In some terrestrial forms the elytra are fused. Ventral surface of the thorax very variable, coxae contiguous to widely separated, sometimes with grooves for the antennae and legs. Abdomen generally with the two basal ventrites connate, only very rarely free, tergites 7 and 8 form a pygidium which is generally hidden beneath the elytra although any exposed segments tend to be heavily sclerotized or sulcate. Legs extremely variable, often long and robust with the femora clavate and the tibiae toothed internally and/or apically. Some species of Rhamphini have greatly enlarged hind femora which allow them to jump in much the same way as the alticine Chrysomelidae. Tarsi generally 5-5-5 with the third segment bilobed and the fourth diminutive, the terminal tarsomere is often elongate. In most with paired claws, sometimes connate and undeveloped, often free and lobed basally, sometimes serrate etc. Scolytinae and Platypodinae differ from the rest; they are small beetles, 1-9mm but mostly between 1 and 4mm, cylindrical or weakly flattened dorsally and most are heavily sclerotized, the majority are drab black or brown and pubescent, in some with distinct scales. Distinguished from other groups by the presence of pre-gular sutures; a distinct pre-gular sclerite between the median gular suture and labial articulation, the rostrum is short or absent and the tibiae, or at least the pro-tibiae, possess teeth or recessed stout setae along the outer margin.

In general the larvae are curved and cylindrical, lightly sclerotized and finely pubescent, and most are pale with the head darker. Head hypognathous and distinct, not recessed into the prothorax, the frontal impression Y-shaped and not extending to the base of the mandibles, endocarina generally present. Stemmata usually absent. Frontoclypeal suture present, labrum free and usually with 4 pairs of setae. Antennae 1 or 2 segmented, the apical segment sometimes conical. Maxillary gala and lacinia fused to form a mala, palpi usually 2-segmented. Labial palps 1-segmented, rarely 2-segmented. All lack distinct legs although some have very rudimentary thoracic and sometimes also abdominal legs. Spiracles are usually present on the prothorax or between the pro- and mesothorax. Each abdominal segment is crossed by 3 or 4 transverse grooves, often with distinct plicae between. Larvae of Scolytinae and Platypodinae are not readily distinguished from the other subfamilies.

Ecology

Members of the Scolytinae and Platypodinae are mostly saproxylic with relatively few species developing in herbaceous plants or seeds, larvae feed on plant material or ‘ambrosia’ fungi that grow in their subcortical and often characteristic galleries. A wide range of both coniferous and broad-leaved trees host these species and the larvae can cause extensive damage when their galleries traverse wide areas of bark destroying phloem vessels etc., Dutch Elm Disease caused by Scolytus is the most notorious example but many species cause extensive losses to the forestry industry and for this reason there is a great deal of knowledge available regarding various species. The U.K. fauna is diverse and varied and so forms an excellent introduction to the groups. Regarding the more typical weevils it is probably true to say that almost every kind of plant in any terrestrial or wetland habitat has its associated species. Most species are phytophagous both as larvae and adults, feeding and developing mostly on angiosperms but also gymnosperms, particularly conifers of the Pinaceae. Most species are monophagous or oligophagous and in many regions, the U.K. being an excellent example, the weevil-host associations are generally well understood. Species with limited hosts generally feed little as adults and may be collected from flowers, or they may feed on leaves, flower parts or seeds while the larvae feed on various plant structures, either internally in stems or roots or as leaf-miners or, as in many Hyperinae and Ceutorhynchinae, externally on leaves or flower parts. Feeding strategies may vary widely within a single genus e.g. the widespread Hylobius abietis (Linnaeus, 1758) feeds on pine while H. transversovittatus (Goeze, 1777) feeds on Lythrum and is restricted to dry peaty soils in the southwest of England. Members of the Entiminae are more generally polyphagous with larvae developing in the soil and feeding upon roots and rhizomes, and adults feeding on foliage. Some Molytinae have reduced eyes and are adapted to live in the soil or among leaf-litter consuming organic debris. As well as the Scolytinae and Platypodinae some members of Cossoninae, Molytinae and Conoderinae feed on dead or decaying wood as well as other dead plant material. A few species are associated with ants but obligate associations are only known so far among some Cryptorhynchinae. Many species of Baridinae, Ceutorhynchinae and Entiminae are associated with grasslands while many Entiminae also occur in deserts, having formed associations with arid-adapted plants. Many species of Entiminae, Ceutorhynchinae, Cyclominae and Bagoinae are associated with freshwater plants and wetland habitats generally while a few species, mostly in Cossoninae, develop in driftwood or seaweed in intertidal zones. In general each biotope will have an associated weevil fauna; as well as the more generally distributed and common species such situations as sand dunes, calcareous grassland and woodland, moorland and wetlands will have many specialist species and so as many habitats as possible should be worked in order to appreciate our weevil fauna. Many species are nocturnal, especially among the Entiminae, and so evening and night-time sweeping of herbaceous and arboreal foliage will generally be rewarding. Many will need to be looked for on the ground e.g. many flightless Entiminae, and carefully searching wetland margins, especially where these are drying up in the summer, is a good way of finding Bagous species. Species of several subfamilies have become economic pests, the most obvious examples being various pests of Brassica crops, the notorious vine weevil which will develop among the roots of a wide range of potted ornamental and crop plants, and some species of Curculio Linnaeus, 1758 which occasionally affect commercial nut crops. Some oligophagous species have been transported from their native range to be used as biocontrol agents to help control invasive weeds, themselves often non-native introductions, among crops.

UK Subfamilies

BAGOINAE

MOLYTINAE

Further Reading

Beetles of Britain and Ireland vol. 4

Andrew G. Duff

Provides keys and accounts on all the UK species.

Die Rüsselkäfer Baden-Württembergs

J. Rheinheimer, M. Hassler

Covers all weevil groups of central Europe (German text only).

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