Taeniapion urticarium (Herbst, 1784)
This species, our only representative of the genus in the U.K., is almost entirely confined to Southern England below a line drawn from the Wash to the Severn Estuary; there are no records from the West Country and only a few very scattered records from Wales (NBN, 2016). It is of very local occurrence although this may be due partly to difficulty in recording the species; it is very small and inconspicuous and so may be overlooked in the sweep net. Furthermore, at least in our experience in the South Hertfordshire area, it can be generally abundant for a year or two and then more or less absent during the following four or five years. Adults can be surveyed by sweeping or beating the host plants, in the U.K. exclusively common nettles, Urtica dioica L., but on the continent maybe also Urtica urens L., from late spring until the autumn although in mid-summer they tend to be present only in small numbers if at all. They occur in a wide variety of habitats; parkland, riverbanks, gardens and wasteland etc. wherever the host plant is abundant. The eggs are laid in early summer in the stems of the host; the female uses her rostrum to excavate a deep round hole in the stem before inserting a single egg, generally near the leaf nodes. The larvae feed within the stems and their presence can be detected by a dark discolouration along the feeding galleries. Development is rapid and pupation occurs in the larval gallery, a single stem may host several larvae and pupae. The pupal stage lasts between fifteen and twenty days and the adults eclose in late summer or autumn, overwintering in the stem and emerging the following spring.
The overall colour and the extent of the elytral markings varies but in the field they appear pale, they usually move slowly or remain still and so are easily overlooked but with a little experience they soon become obvious.
Taeniapion urticarium 1
© Dave Hodges http://thewcg.org.uk/
Taeniapion urticarium 2
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
Tiny beetles, 1.9-2.3mm, narrow and elongate with a dark body and pale appendages. Head and pronotum black, elytra black with reddish areas, especially laterally. Head densely punctured and with sparse elongate and pale scales which continue along the rostrum in the male. In the female the rostrum is glabrous beyond the antennal insertions. Antennae inserted near the base of the rostrum where it is distinctly dilated. Pronotum quadrate; broadest at the base and gradually narrowed towards the apex, the surface usually depressed in front of the hind margin. Sparsely scaled, obscurely punctured and densely granulate. The hind margin is strongly sinuate, the hind angles acute and produced laterally. Elytra elongate and narrow with the striae deeply impressed and punctured. Interstices about as wide as the striae, and strongly granulate. With a distinct pattern of two transverse bands and the apical region, which comprises a mixture of two types of scales; longer and broader which are almost white, and shorter and narrower scales which are pale brown. The legs are long and slender; the femora, tibiae and basal tarsal segments with pale scales.
TAENIAPION SCHILSKY, 1906
This is a small genus of about 7 species, depending upon how the limits of the genus are defined, with a widespread Palaearctic distribution. A further group of 5 Afrotropical species is sometimes included. They are small species, up to about 4mm in length, characterized by the distinctively patterned elytra, the rostrum being weakly dilated near the base around the antennal scrobes and a deep excavation on the ventral surface of the head. They are associated with various Urticacaea e.g. Urtica L. and Parietaria L. where development occurs within the stems. The most widespread member of the genus, T. urticarium (Herbst, 1784), occurs throughout Central Europe north to Scandinavia and east to Siberia and is the only species to occur in the U.K. While several species are widespread across the Western Palaearctic, T. rufescens (Gyllenhal, 1833) is more restricted to Southern and South eastern Europe, and T. rufulum (Wencker, 1864), as well as occurring throughout Central Europe and Western Asia, also occurs in Morocco.