Calomicrus circumfusus (Marsham, 1802)
This Western Palaearctic species occurs mostly in Central and Northern Europe, from The Pyrenees to Italy, Austria and Ukraine, to the north it reaches the UK, Denmark and Poland but is otherwise absent from the Baltic region. To the east it extends into parts of Western Russia and it is also known from Bulgaria, where it has been recorded up to 1700m, Morocco and Tunisia. Throughout most of this range, but especially towards the north, it is local and sporadic and it is thought to have declined over recent decades. In the UK it is widespread across England north to the Humber and there are older records further north into Central Scotland, it is generally very local and scarce although there are strongholds in Hampshire and the Isle of Wight where it may be common, and it is often common in coastal locations in the West Country. Adults are active from April until September or October and peak in abundance during July and August; they are rarely found outside this season and are not known to overwinter. Typical habitats are heathland, moorland, grassland and scrub, open woodland and maritime meadows and cliffs. Host plants include various Fabaceae, in the UK mostly Gorse (Ulex europaeus L. and U. minor Roth.) and broom (Cytissus scoparius (L.) and C. striatus (Hill.)) but also greenweeds (Genista tinctoria L. and G. pilose L.) and Spanish broom (Spartium junceum L.), and on the continent it has been recorded from Adenocarpus DC., Genista cinerea (Vill,), G. florida L., G. sagittalis L. and G. scorpius (L.). Adults feed extensively on host foliage before mating from late spring. Females lay small batches of eggs in the ground among host roots and each may produce up to fifty eggs. Larvae develop through the summer and move deeper into the ground as final instars during the autumn to overwinter. Larval development is completed early in the year and pupation occurs in a subterranean cell from April. Adults may be sampled by sweeping host foliage, they usually occur in small numbers but they fly well and may swarm about host foliage on hot summer days, they can be very active in the sweep net and tend to take flight when alarmed. Gravid females tend to remain on low foliage or on the ground, they may become greatly distended and are therefore easily recognized and so should be left alone.
Calomicrus circumfusus 1
2.5-4.5 mm. Easily identified by the long-oval form and distinctive colour. Dorsal surface glabrous and shiny, head and ventral surface black, pronotum yellowish with various darker markings on the disc and along the base, elytra yellowish with dark margins, legs extensively pale but with the femora and tibiae variously darkened, antennae dark, usually with four or five pale basal segments. Head with well-impressed frontal tubercles between large and convex eyes, vertex smooth and very finely punctured, antennae slender and filiform, with segments two and three subequal in length. Pronotum transverse, widest about the middle and smoothly curved and finely bordered laterally, surface smoothly convex and finely punctured throughout. Elytra dilated in females, almost parallel-sided in males, from rounded shoulders to separately rounded apical margins, surface without striae, finely punctured and roughened and usually with fine setae towards the apex. Legs long and slender with femora and tibiae all of more or less equal width. All tibiae with a singly apical spur in both sexes. Tarsi pseudotetramerous, claws appendiculate. The general form will distinguish the sexes but in doubtful cases may be distinguished by the impressed and notched apical sternite, in females it is smoothly convex and the apical margin is entire.