Cartodere nodifer (Westwood, 1839)
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POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
LATRIDIINAE Erichson, 1842
Aridius Motschulsky, 1866
Native to Australia and New Zealand this species is now cosmopolitan in distribution having been transported worldwide with the trade in foodstuffs etc; the earliest record from the United States was prior to 1894 and the first European record was from England in 1839, the spread was rapid during the eighteenth century and it is now firmly established both in the wild and as a pest throughout the world. In the UK it is now common or abundant throughout England and Wales, including the islands, and scattered and generally scarce through Scotland north to Orkney. Both adults and larvae feed exclusively on fungal hyphae, spores and conidia developing on damp surfaces, thus they occur inside on a very wide range of foodstuffs, clothing, leather goods, books and stored paper etc, they develop among mould forming around window frames or under loose floor coverings, or on any poorly ventilated and undisturbed surface, and the common name refers to their frequent occurrence around loose wall-paper, where they feed on mould forming on damp paste, and on white-wash applied to plastered walls and ceilings. In the wild the species is common among compost, leaf-litter and, unusual for the family, in old and dry dung, they occur in bird, mammal and hymenopteran nests and may be common under damp bark and logs etc. They are nocturnally active and at night might be found in any damp situation hosting slime-moulds or other fungi; in our experience the sawn-ends of logs left for a few months to develop moulds will often host large populations of the beetles and their larvae, they become active in the evening and remain so through the night, and often these will include a number of the superficially similar C. bifasciata (Reitter, 1877). Adults occur year-round; searching any not-too-dry habitat might be expected to reveal the species, during the summer they often appear when sweeping vegetation generally and through the winter they regularly occur among extractions from grass tussocks, litter and, especially, all kinds of fungi. Inside the species may breed at any time and, under suitable conditions, may be continuously-brooded, in the wild we have observed mating pairs in late spring and early summer. Eggs laid on the surface of mouldy bread and cheese in Petri dishes kept around 60°F hatched within 5-7
days. First and second instar larvae developing on moulds moulted after 6 days and third (final) instar larvae ceased feeding after 5 or 6 days and attached themselves to the substrate using an anal secretion, they remained in this position for 2 or 3 days then pupated. Adults eclosed after 3 or 4 days and the entire cycle from egg to adult varies from 27 to 32 days. Freshly eclosed adults are pale testaceous, they take between 7 and 10 days to fully darken and during this time they develop the membrane-like secretions bordering the pronotum.
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​These tiny beetles are readily identified by the overall dark colour and the elytral sculpture. 1.2-2.1mm, elongate with the forebody narrower than the elytra, separately rounded and strongly convex. Colour when mature dull black and mature specimens have a waxy membrane to the sides of the pronotum and on various parts of the ventral surface. Head densely and strongly punctured, with a variable longitudinal median depression and strongly convex eyes, temples about as long as the eyes and parallel or weakly converging to distinct posterior angles. Clypeus truncate and finely punctured, labrum broadly rounded and only very finely punctured. Antennae slender and relatively long, with a 3-segmented club. Pronotum broadest behind rounded anterior angles, deeply transversely constricted in the basal third, the lateral margin almost straight posterior to this and rounded anteriorly, basal margin almost straight. Surface strongly rugose and punctured, with a distinct ridge either side of the middle which is straight in the basal half and curved anteriorly. Lateral margins of the pronotum and elytra very finely crenulate. Elytra rounded laterally and explanate about the middle, with a wide and shallow transverse impression across the basal third which extends to the fifth stria. Each elytron with 3 strongly raised carinae; one in the second interstice which is sometimes only obvious in the basal quarter, one in the fifth interstice strongly raised and complete almost to the apex, and one in the seventh interstice strongly raised and curved over the shoulder and extending at least to the middle. Legs long and slender; male pro- and meta-tibiae with a fine spur on the inner apical angle and a prominent tooth on the inner margin of the meta-tibiae towards the apex; both of these characters are missing in the female. The meta-tibial tooth is unique to this species. Both sexes are distinct among our fauna in having the third interstice raised into an elongate tubercle over the elytral declivity.