Donacia versicolorea (Brahm, 1791)

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POLYPHAGA Emery, 1886

CHRYSOMELOIDEA Latreille, 1802

CHRYSOMELIDAE Latreille, 1802

DONACIINAE Kirby, 1837

Donacia Fabricius, 1775

This very widespread species occurs throughout most of the Palaearctic region from Portugal and southern Spain to the far east of Russia, it is locally common in Europe from the Mediterranean to the UK and Scandinavia where it almost reaches the Arctic Circle, it mostly occurs in lowlands and foothills but extends above 2000 m in the Pyrenees. It is locally common across the UK and Ireland with the exception of Orkney, Shetland and some of the Western Isles and while it is absent from many of the Highland areas it is generally the most common member of the genus in Scotland. Typical habitats are wetland margins and shallows; rivers, reservoirs marshes, canals and drainage ditches and moorland and heathland pools but they can be common at small cattle ponds and even garden ponds that are left to nature, in fact anywhere the host plants, which include species of pondweed (Potamogeton L, but usually P. natans L. and P. perfoliatus L, less often P. polygonifolius Pourr.), grow in abundance. Adults appear during May and persist into September or October, they usually occur in numbers and often on a range of marginal and floating foliage such as Sweet-grass (Glyceria (L.)) or various reeds (Phragmites Adans and Sparganium L.) and rushes (e.g. Juncus L.) and are sometimes common on water lilies (Nymphaea L.) and arrowhead (Sagittaria L.), they feed by scraping away at the upper epidermis and leave irregular holes or wavy lines of translucent membrane. Mating occurs on the surface of leaves etc. during May and June and females oviposit in July and August. Eggs are laid in groups of 20-30, usually placed in short parallel rows on the underside of leaves, and covered in a protective jelly which often bonds several leaves together and hides the eggs from aquatic predators. Larvae emerge after a week or two and, while the details are not known, probably feed among the roots and almost certainly overwinter in this habitat and continue developing in the spring as empty cocoons have been found on Potamogeton rhizomes in August. Adults are large and very distinctive in appearance, they are active among foliage in hot weather but otherwise remain still on stems and leaves, either way they are easily spotted and swept although when disturbed they may instantly drop or take flight and become very difficult to find.

Donacia versicolorea 1

Donacia versicolorea 1

Donacia versicolorea 2

Donacia versicolorea 2

Donacia versicolorea larva

Donacia versicolorea larva

5.5-9.0 mm. Body glabrous, metallic bronze or coppery, often a with green or red reflection, legs substantially dark but the base of the femora and at least part of the tibiae are paler reddish-brown, antennae dark with the base of most segments reddish. Adults are often obvious in the field due to the massive hind femora, and in certain lights the elytral punctures appear as bright points against a dark background. Head concave and densely pubescent between large and protruding eyes, and robust but short mandibles that do not protrude forward. Pronotum quadrate to very slightly transverse, broadest in front of the middle and constricted in the basal half, posterior angles obtuse and anterior angles slightly projecting, surface with a distinct longitudinal median impression, transversely rugose throughout and strongly punctured across the disc. Elytra flattened and in side view gradually tapered from the base to the apex, without a marked apical declivity, with complete and strongly punctured striae which often become confused towards the base, and shiny, almost impunctate interstices.  Hind tibiae with several small tubercles along the inner margin in the apical half. Male with two teeth on the ventral margin of the hind femora, females with a much smaller tooth which may be almost obsolete.