Apteropeda orbiculata (Marsham, 1802)

A local and often locally common species occuring throughout England and Wales including the Isles of Wight, Lundy and Anglesey although there are large areas of north Wales and northwest England without modern records and in the west country most records are coastal. From Scotland there are a few modern records from the south, north to ayr, and a single, isolated record (pre-1990) from the far northwest around Ullapool (NBN Aug 2009). Cox includes a record from Man. Locally we have recorded adults throughout Whippendell and adjacent woods and in most years they are common; they occur among grass and mixed vegetation beside the pathways etc and from April or May can be found visiting a wide range of flowers, often in numbers and apparently indifferent to sun or shade. Beyond this they are known to occur in a wide range of habitats eg calcareous grassland, heaths, scrubland, road verges and riverbanks. The species is widely polyphagous on herbaceous plants, although Corylus (Hazel) is also quoted by Cox, with perhaps a preference for Lamiaceae; adult feeding produces small round holes in the foliage. Among the species recorded as adult or larval hosts are Plantago spp. (Plantains), Aster spp., Bellis perennis (Daisy), Carduus spp., Cirsium spp. (Thistles), Ajuga reptans (Bugle, with which the species is often associated with in local woods, A.genevensis, Calamintha vulgaris, Clinopodium vulgare (Calamints), Galeopsis tetrahit (Hemp nettle), Glechoma spp. (ground ivy), Lamium (deadnettles), Prunella spp. (self heals), Stachys spp. (woundwort) Teucrium spp. (germanders), Verbascum lychnitis (white mullein), Veronica chamaedrys (German speedwell), Digitalis spp. (Foxglove), Linaria spp. (toadflax), Pedicularis spp. (Louseworts), Rhinanthus spp. (hayrattles), Scrophularia spp. (figworts) and Primula spp. (Primroses) (Bladmineerders). Adults occur year round, spending the winter in leaf litter or moss etc and becoming active in early spring. Oviposition begins in April; single eggs are laid within the leaf near the edge or the tip and the larva upon emerging begins a mine, initially a shallow upper surface mine and later full depth British leaf miners); the mines are erratic although may comprise straight runs and often cross over. Larvae regularly leave the mine and begin a new one, the final mine is wide and more like a blotch. Fully developed larvae leave the mines and pupate within an earthen cell in the ground, and new generation each year.

Both sites mentioned above feature excellent photographs of the leaf mines, British leafmines feature a photograph of the larvae. So far as is known the larvae and mines cannot be distinguished from other Apteropeda species.

These tiny and bright metallic flea beetles soon become familiar in the sweep net, as unfortunately does their habit of seeming to vanish as they rapidly hop out. The overall shape is distinctive when compared with other small metallic species eg Chaetocnema

2.2-2.6mm. Vey convex and broadly oval, shiny metallic; green, blue, violet, copper or bronze, apparently without microsculpture (X20). Head not, or only just, visible from above in normal setting, finely and quite densely punctured and with two transverse raised lines between eyes. Eyes transverse and weakly sinuate before antennal insertions. Antennal calli small and close together; much closer than the length of the basal antennal segment. Mouth parts projecting forwards and downwards. Antennae 11 segmented, testaceous becoming darker apically, segments four and five equal in length or nearly so. Pronotum strongly convex, surface finely punctured otherwise without impressions, lateral margins finely bordered; this border runs behind the weakly projecting, acute front angles. Hind angles obtuse. Scutellum very small, hardly visible. Elytra glabrous, each with nine regular rows of large punctures and an abbreviated scutellary row, interstices finely and randomly punctured. Hind femora greatly expanded, black or dark metallic and strongly pubescent beneath. Legs otherwise testaceous. Hind tibiae with a sharp pointed spur inside at apex, upper surface with two longitudinal ridges, the outer of which has a series of five or six teeth from before middle towards apex. Hind tarsi attached to apex of tibiae, basal segment about as long as second and third combined. Front and middle femora not dilated, these generally need to be examined from the side. Tibiae without dorsal ridges and lacking a terminal spine. First segment of front and mid tarsi proportionally not so long as those of hind tarsi. Closely similar to A.globosa see ID Aids.

Description from 2 Watford specimens at X20