Neocoenorrhinus pauxillus (Germar, 1824)
Widespread in lowland to low mountain altitudes in central and southern Europe but rather sporadic further north to southern Sweden and the UK, this species is generally rare and very local across its European range but may be locally common further south and east where it extends through the Caucasus, Asia Minor and Iran to central Asia. In the UK it is a very rare species, it occurs mostly in eastern England as far north as Cambridge but there are also a very few scattered records further north to Durham. The species is polyphagous on a range of rosaceous trees and shrubs and in Europe is an occasional pest of fruit trees, mostly apple and pear but occasionally plum (Prunus domestica L.) and quince (Cydonia oblonga Mill.) among others, in the wild the main hosts are Crataegus Tourn. Ex L. (hawthorns), Prunus spinosa L. (blackthorn) and Mespilus Bosch ex Spach (Medlar) and various ornamental trees and shrubs of the genera Cotoneaster Medik, Sorbus L. and Rosa L. have been recorded hosting the species. Adults are active over a short season from April until June; they emerge from the ground and browse on tender fresh foliage causing numerous shot-holes in the leaves, but this does not harm the plants as the leaves generally continue to develop normally. Mating occurs after a period of feeding and oviposition proceeds from early May; females lay egg singly or in small numbers on the underside of leaves at the base of the midrib and the partly sever the petiole, causing the leaf to wilt and fall soon afterwards but the leaves remain green for several weeks. Larvae emerge after a week or so and tunnel a short distance into the midrib before moving into the leaf to produce broad blotch mines which become lined with frass, and each leaf usually hosts several larvae which mine galleries in opposite directions or parallel to each other along the midrib. Larvae grow rapidly and are fully developed within 2 to 4 weeks, at which time they emerge from the leaf and enter the ground to pupate, this stage is also rapid and adults are fully formed a few weeks later but they do not emerge and will remain in the soil until the following spring. In some parts of Europe occasional large populations form which can extensively defoliate commercially-grown saplings and young trees, causing their growth to slow or having adverse effects on their development.
2.0-3.3mm. Body, including the base of the rostrum, dark blue or bluish-green, apex of rostrum black, legs black with a weaker metallic reflection, dorsal surface with rather sparse long, erect brownish pubescence. Head transverse and strongly and densely punctured; the punctures slightly smaller but closer than those on the pronotum, eyes large (distinctly larger in the male), convex and prominent, rostrum rather strongly curved in both sexes but a little shorter in the male. Pronotum transverse and rounded laterally, the basal margin distinctly wider than the apical margin, surface evenly convex or with an indistinct longitudinal basal fovea, and strongly and discretely punctured throughout. Elytra elongate (about 4:3) and much broader across the base than the pronotum, with prominent and slightly forwardly-produced shoulders and weakly dilated towards a continuously rounded apical margin, striae, including a scutellary striole, strongly punctured and complete to the apex except for the ninth which terminates or appears to merge with the tenth about the middle (similar to that seen in Lasiorhynchites comatus, which is larger and has more elongate elytra), interstices convex, especially towards the lateral margins, about as broad as the striae and very finely punctured.