HYPERINAE Marseul, 1863
Includes several common species, which can be found on a range of herbaceous vegetation. Unlike most weevils, adults generally occur in small numbers.
POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
In weevil terms this is a small subfamily of about 500 species in about 44 genera and two tribes. Cepurini Capiomont, 1867 includes about 100 species of 15 genera distributed in tropical regions worldwide, the genera tend to be restricted to particular areas such as Central or South America, Africa, southeast Asia or Australia, it is not represented in the Nearctic region and only a single species, Fronto capiomonti Faust, 1882 occurs in the Palaearctic region (eastern Siberia). Compared with northern temperate regions, the tropics are generally poor in diversity; about 40 species occur in the Neotropical region, less than 20 in tropical Africa and about 45 species occur in the Australian and Pacific region. Hyperini Marseul, 1863 is a mostly Old World group comprising about 400 species in 44 genera with by far the greatest diversity in the Palaearctic region, several genera are endemic to particular areas e.g. the Australian Lycosura Pascoe, 1875 and Agriochaeta Pascoe, 1872, Lamprohypera Heller, 1908 from New Guinea or the Neotropical Diastrophilus Faust, 1892, and the Nearctic fauna is small with about 20 species, which includes introductions as well as some natives of the large Holarctic genus Hypera Germar, 1817. The Palaearctic fauna includes about 380 species in 17 genera, of which about 150 species of 10 genera occur in Europe, the highest diversity is in southern regions and only 16 species of 3 genera extend to the UK, and with only two exceptions these are otherwise very widespread Eurasian species; Hypera ononidis (Chevrolat, 1863) and Limobius mixtus (Boheman, 1834) being more restricted to western Europe and North Africa.
The position and status of this group is still uncertain; it is presented here as a distinct subfamily of the Curculionidae for convenience only as this has been in widespread use in the literature and in recent checklists but various other systems will be found and it is probably safest to regard it as an unplaced tribe within the family. The group is very difficult to define in morphological terms and it is usually described by lists of features such as the form of the pygidium, trochanters and claws but none are unique to the group and the classification and taxonomy is likely to change, especially at the generic level. The two tribes discussed above are separated on the form of the mesepimera and their orientation with respect to the metanepisterna, but in many cases they are otherwise very similar.
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
© Mark Gurney
Features unique to the group can be found in their development; larvae live freely on the surface of leaves and superficially resemble lepidopteran caterpillars, they also behave like them and at least one Neotropical species, Phelypera distigma (Boheman, 1842) forms processionary columns like moths of the Thaumetopoeidae, laying down pheromone trails as they go. They also construct delicate lace-like cocoons on the host plants in which to pupate. Where known all species feed on foliage or herbaceous stems and the habit of building a cocoon seems to be general in the group, some tropical species e.g. members of the Australian genus Gerynassa Pascoe, 1873 (Hyperini) mine leaves as larvae but they also emerge to construct cocoons in which to pupate. Larvae construct cocoons after they have finished developing, these are tough and often elaborate structures made up of a rapidly drying protein matrix secreted from the Malpigian tubules , they vary in colour and build and are attached to trunks, leaves or stems, they often have an open structure but the mesh is close enough to protect the pupa from parasites or predators such as assassin bugs, and in many cases the adult consumes, or partly consumes, the cocoon shortly after emergence. In temperate northern regions members of the group feed on plants of a wide range of families but mainly Apiaceae, Fabaceae, Geraniaceae, Boraginaceae, Carophyllaceae, Lamiaceae, Polygonaceae and Saxifragaceae, and UK species, as well as members of the large genera Brachypera and Hypera generally, tend to be oligophagous. Species of some continental genera e.g. Donus Jekel, 1865 may also be monophagous or polyphagous. Several species are minor pests of agricultural crops but two; Hypera postica (Gyllenhal, 1813) and Brachypera zoilus (Scopoli, 1763) are occasionally very serious pests of clover.
Our UK fauna can be distinguished by the following description although with a little experience they soon become familiar. Medium sized weevils, 3.1-8.5mm, elongate and rather flattened with a small, transverse head, quadrate to transverse pronotum which is curved laterally and wider than the head and elongate elytra with broad shoulders which are much wider than the pronotum, parallel-sided in the basal half and continuously rounded apically and covering the abdomen. Many have distinctive, though variable, patterns of scales to the pronotum and/or elytra and most species of Hypera can be recognized by the bifid form of these scales, in extreme cases e.g. H. nigrirostris Fabricius, 1775 they are long and divided almost to the base while in Limobius they are truncate or only weakly bifurcate. Rostrum moderately long, at most 3.5 longer than wide at the base, weakly curved and usually parallel-sided, it may widen gradually from the base so that the apex is distinctly wider but it is never dilated in the apical half, scrobes placed laterally and not visible from above. Eyes elliptical and weakly convex, usually occupying most of the lateral margin of the head. Antennal scape short, generally only a little longer than the head-width, and rather abruptly thickened in the apical third, funiculus with six (Limobius) or seven segments, club three segmented, pubescent and usually distinctly elongate. Pronotum without lateral or anterior borders, surface simply convex and usually finely and densely punctured though this is often obscured by scales. Metathoracic epimera not visible beyond the elytral humerus or pronotal base from above. Elytra smoothly convex, without raised interstices or grooves, the vestiture usually consists of dense scales and a row of variously-developed long setae in each interstice, there may also be shorter erect or semi-erect setae among the scales on the pronotum and/or elytra and these are usually obvious along the lateral margins. Legs long and robust. Anterior femora without an internal tooth, anterior tibiae curved internally at the apex, sometimes only weakly so, to produce a sharp angle. Tarsi pseudotetramerous, the small fourth segment often obscured by the bilobed third segment. Claws separate to the base, smooth and lacking a basal tooth.
Of our two species of Brachypera, only B. zoilus is common, though very local, in England and Wales, it also occurs to the far north of Scotland but here it is generally scarce. Host plants include a range of clovers. B. dauci (Olivier, 1807) is very local and generally rare in East Anglia and around the welsh coast, hosts include various Geraniaceae. Several of our Hypera species e.g. H. rumicis (Linnaeus, 1758), H. nigrirostris (Fabricius, 1775), H. arator (Linnaeus, 1758), H. venusta (Fabricius, 1781), H. plantaginis (De Geer, 1775) and H. postica (Gyllenhal, 1813) are widespread and generally common, a few others e.g. H. meles (Fabricius, 1792), H. pollux (Fabricius, 1801) have a more restricted southerly distribution and some are very rare and local e.g. H. pastinacae (Rossi, 1790) from the Kent coast, or H. ononidis Chevrolat, 1863 from southern coasts, and one of our listed species, H. arundinis (Paykull, 1792) is thought to be long extinct. Our Hypera are oligophagous on a range of plant families. Neither of our two species of Limobius Schönherr, 1843 are common; L. mixtus (Boheman, 1834) was widespread in the south but is now known only from coastal East Sussex while L. borealis (Paykull, 1792) is widespread but very local and sporadic across Wales and central England. Both are associated with Erodium cicutarium (L.), common stork’s-bill, where the larvae develop among unripe flower buds.