Antherophagus Dejean, 1821
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
CRYPTOPHAGINAE Kirby, 1826
CRYPTOPHAGINI Kirby, 1826
A. pallens (Linnaeus, 1758)
A. silaceus (Herbst, 1792)
A. similis Curtis, 1835
This small genus includes some of the largest members of the family. Four species are known from North America, five have been recorded from Europe and none are Holarctic. Three of the European species are widespread and extend to the UK while the other two are widespread Asian species: A. fursovi Lyubarsky, 1991 extends into southern parts of European Russia, and A. caucasicus Reitter, 1878 occurs in Ukraine and southern parts of European Russia. All are highly specialized phoretic species with larvae developing among detritus in nests of various bees, there are no specific associations and it is likely that all species are generalists adapted to developing in nests of a range of species. Adults do not seek out nests but are generally associated with flowers where they have been observed to feed on pollen and nectar, and where they wait to attach themselves to visiting bees. White flowers seem to be preferred by the beetles which often on various shrubs, umbels, blackberry and white-flowered labiates, but they fly well and in warm weather they may be netted from a range of situations while sweeping. They usually occur in small numbers. Mating occurs on flowers etc. and females attach themselves to bees, after entering the nest they remain attached for some time and may resist attempts by the bee to dislodge them, but eventually they find their way to the base of the nest and lay eggs among the detritus. Adults of both sexes have been found in nests during the summer which suggests that males also attach themselves to bees. There have been numerous accounts of adults attached to the legs or proboscis of bees in flight but the sexes have not been recorded. (There are some interesting accounts HERE.) In some accounts the larvae are quoted as entering the brood cells and consuming honey but this seems not to be the case and they are now considered to be harmless scavengers. Adults are seasonal, occurring between May and September and peaking in abundance during June and July, although individual specimens occasionally occur in nests during the winter which might suggest that larval development is completed during the summer and autumn and that winter is spent either in the larval or pupal stage.
Antherophagus similis 1
Antherophagus pallens 1
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
Antherophagus pallens 2
Antherophagus similis 2
© U.Schmidt https://www.kaefer-der-welt.de/index.htm
At 3.0-5.0 mm these are the largest of the European cryptophagids, they are also very distinctive in appearance and so should be easily identified, at least to genus, in the field. Elongate and discontinuous in outline. Head proportionally large but narrower than the pronotum, elytra broader across the base than the base of the pronotum although in UK species sometimes only slightly so. Head broadest across weakly convex eyes, cheeks converging to an emarginate clypeus and temples short and slightly protruding behind the eyes. Surface punctured and pubescent throughout, without structure but often with indistinct transverse impressions towards the base. Mandibles curved and bidentate. Antennae inserted laterally under the outer margin of the mandibles, 11-segmented with an enlarged basal segment, 2-8 quadrate or slightly transverse, and 9-11 forming a loose club. Pronotum transverse and only weakly curved laterally, sometimes almost straight, lateral margin smooth and bordered to obtuse posterior angles and rounded (from above) anterior angles. In side view the lateral border sometimes fades before an oblong and flat callus which is not, or only very narrowly, visible from above. Pronotal surface evenly punctured and pubescent throughout, without distinct structure but usually with one or two depressions either side in front of the base. Scutellum widely transverse, broadened from the base and truncate apically. Elytra gently curved from angled or weakly-rounded shoulders to continuous or separately-rounded apical margins which completely cover the abdomen. Elytral surface finely punctured and pubescent, usually a little more finely so than the pronotum, without striae although the suture is finely bordered, at least apically, and there may be shallow and vaguely-defined longitudinal depressions. Legs short and robust. Femora unmodified, thickened and of equal width. Tibiae expanded from the base and obliquely-truncate apically, front tibiae with a single apical spur, middle and hind tibiae with paired spurs. Tarsi 5-segmented in females, 5-5-4 in males, all segments simple. Claws smooth and without a basal tooth. The genitalia seem to be variable and are not useful for identification. Males may be recognized by their thickened antennae and front tarsi and more deeply emarginate clypeal margin. Our three UK species are readily identified from the following key which is adapted from Otero et al (1998).
-Lateral pronotal border abbreviated, not reaching the anterior angle. Pronotum widest across the base, slightly converging towards obtuse anterior angles in females, straighter, more parallel-sided and with the anterior angles slightly extended forward in males. 4.5-5.0 mm.
-Lateral pronotal border (which is sometimes very fine and needs to be looked for very carefully) reaching the anterior margin. Pronotum slightly narrowed towards the base or parallel-sided.
-Dorsal pubescence dense and moderately long, especially on the head and pronotum. Front tibiae produced into an external apical tooth. 4.0-5.0 mm.
-Dorsal pubescence very fine throughout, the pronotum, and sometimes the head, often appearing almost glabrous. Front tibiae not, or barely, produced at the external apical margin.
Antherophagus pallens (Linnaeus, 1758)
Care must be taken with this name when using older literature; it is often quoted by the synonym A. nigricornis (Fabricius, 1787), and pallens was formerly applied to A. similis. This species is locally common across the entire Palaearctic region, from Europe to Japan, although adults tend to be infrequently recorded and always as single specimens or in small numbers. In Europe it extends from Spain through Central France and Northern Italy to Romania and Ukraine and north to the UK and into Southern Fennoscandia and a few sites on the Baltic coast where it is very local and rare. The species is widespread though generally very local and scarce across England and Wales with most records from south eastern England, East Anglia and the West Midlands, it seems to be largely absent from the West Country and much of Northern England although there are older records from Cumbria and Southern Scotland. Adults are generally associated with humid grassland, agricultural and woodland borders and disturbed and waste ground with varied and abundant vegetation. In Northern Europe the species is said to occur commonly on flowering Raspberries (Rubus fruiticosa L.)
Antherophagus silaceus (Herbst, 1792)
Although very widespread and occurring from Europe and Asia Minor to the far east of Russia, this species is generally very local and uncommon. In Europe it is by far the least frequently recorded of our three species and is generally very local and sporadic, especially towards the Mediterranean. To the north it reaches into the UK and the southernmost provinces of Fennoscandia but, again, it is seldom found in numbers and records are widely scattered. There are very few records from the UK, mostly from Southern England and South Wales although it has also been recorded from Ireland, and the majority are from coastal or near-coastal sites. Adults occur from June until September although individual specimens occasionally occur later, and they peak in abundance during July. They are typical of the family in occurring on flowers generally but they seem to prefer low herbaceous plants rather than flowering trees and shrubs. The species seems to prefer open and well-vegetated heathland and dry grassland sites on light or sandy soils, at least in Northern Europe, and is often recorded from coastal dunes etc. Adults have been found on flowers on recently disturbed sites, and larvae have been recorded from nests of the Red-tailed Bumblebee (Bombus lapidarius L.).
Antherophagus similis Curtis, 1835
This Palaearctic-wide species occurs from Europe through Asia Minor and Russia to the Pacific coast. It is widespread across lowland Europe, extending from the Mediterranean to above the Arctic Circle in Scandinavia, and is generally the most frequently recorded member of the genus. In the UK it is generally absent from the West Country but otherwise locally common across England and Wales as far north as the Humber, including the islands, and much more local and scarce further north into southern Scotland and there are a few isolated records from the Scottish Highlands, Orkney and Northern Ireland. Adults are active from May until August or September and peak in abundance during June and July. In southern and central Europe the phenology seems to be much the same but in the north they seem to be active over a much shorter season, for about six weeks, from May to July. The species occurs in a variety of not-too-wet habitats with a varied flora including deciduous and mixed woodland, dry grassland, heathland and parkland and often occurs on disturbed sites. Adults are easiest found by sweeping flowers and foliage but they occasionally occur in flight-interception traps placed in or near to flowering trees and shrubs.