Ceutorhynchus erysimi (Fabricius, 1787)
A common and often abundant species throughout Europe, extending north to the UK and far above the Arctic Circle in Fennoscandia, it is widespread across North Africa and extends east through Asia Minor and Siberia to the far east of Russia, it has also become established and widespread since the 1920s in the United States and Canada following the introduction and spread of its main host plant, Shepherd’s-purse (Capsella bursa-pastoris (L.)). In the UK it is locally common throughout England, Wales and Ireland and much more local and rare further north to the Scottish Highlands, it occurs on Outer Hebrides and Shetland but is otherwise absent from the Scottish islands. Adults occur year-round and are active over a long season from early spring, typical habitats are grassland, arable land and parkland and they are often found on disturbed sites such as wasteland and gardens where the host thrives. In the UK the host seems to be Sheperd’s-purse but on the continent it has been recorded from a range of Brassicaceae and occasionally attacks crops such as kohlrabi (a cultivar of Brassica oleracea L. which includes cabbage etc.). Adults overwinter among litter or in tussocks and emerge early in the spring to begin feeding, mating occurs soon afterwards and oviposition begins in March. Eggs are laid on the underside of petioles or leaves low down on the plant; the female chews a small hole into the plant tissue, inserts a single egg and then seals the hole with secretions. The freshly emerged larva begins feeding by boring along the petiole or midrib and then producing small mines that fan out onto the leaf, it continues mining leaves and can move through the stem to reach fresh foliage but as it grows it will mine the stems and when fully-grown will bore down into the roots and enter the soil to pupate. Larvae have been observed from March until May and new-generation adults appear from late June. The host is very common in most habitats and often grows among mixed low herbage and so adult weevils tend to turn up through general sweeping although in our experience they may be common locally but rarely occur in numbers.
Ceutorhynchus erysimi 1
Ceutorhynchus erysimi 2
1.8-2.5 mm. Elongate-oval, discontinuous in outline and very convex, dorsal surface without scales but with fine pale pubescence, ventral surface sparsely clothed with elongate pale scales, forebody black with a distinct metallic bronze or coppery reflection, elytra metallic blue, rarely greenish. Head with convex eyes which reach the rostral base (from above)and diverging temples, closely and confluently punctured and rugose throughout, rostrum long and parallel-sided; in the female the prorostrum is longer than the antennal scape, in the male it is at most as long as the scape. Antennae long and slender, the scape gradually and only weakly broadened from the middle, funiculus 7-segmented, and club narrow and pointed. Pronotum transverse, broadest in the basal third and narrowed to obtuse basal posterior angles and a narrow and raised apical margin, surface strongly punctured throughout and with a small tubercle either side in the basal third. Elytra elongate, broadest behind the shoulders and narrowed to a continuously-curved apical margin which covers the abdomen, striae punctured and impressed to the apex, interstices at least 2X broader than the striae; finely punctured and rugose, in the apical quarter or third with a series of distinct tubercles. Legs long and robust, femora sinuate and without a ventral tooth, tibiae expanded towards the apex; the middle and hind tibiae with a sharp apical spur in the male, simple in the female. Tarsi pseudotetramerous with the third segment widely bilobed. Claws without a basal tooth.