BOSTRICHIDAE Latreille, 1802
False Powderpost Beetles
Associated with dry, dead timber. Lyctus brunneus is nocturnally active, and locally common. Other species are only occasionally encountered in the UK.
Around the World
This is a large and cosmopolitan family of more than 700 described species in about 100 genera and 7 subfamilies with by far the greatest diversity in tropical and subtropical regions. Bostrichinae Latreille, 1802 in the modern sense includes about 55 genera in 5 tribes. The Nearctic, monogeneric Dinapatini Lesne, 1909 includes 2 species of Dinapate Horn, 1886. Apatini Jacquelin du Val, 1861 includes 3 old world genera and is sometimes considered a distinct subfamily. The cosmopolitan Bostrichini Latreille, 1802 contains between 15 and 20 genera including the large and widely distributed Dominikia Browski & Wegrzynowicz, 2000, Lichenophanes Lesne, 1899 and the mostly Neotropical Micrapate Casey, 1898. Sinoxylini Lesne, 1899 includes about 6 genera from Europe, Asia, Africa and South America, the old world genus Sinoxylon Duftschmidt, 1825 includes more than 50 species and is the largest of the tribe, the African Xyloperthodes Lesne, 1906 includes about 20 species. Xyloperthini Lesne, 1921 is a large and widely distributed group of about 35 genera, it includes many endemics e.g. the Sri Lankan Xylophorus Lesne, 1901 with 2 species, Xyloprista Lesne, 1901 is Neotropical and Xylobosca Lesne, 1901 is Australian, while most genera are more widespread e.g. the old world Xylopertha Guerin-Meneville, 1845, Xyloscopus Lesne, 1901 and the mostly African Enneadesmus Mulsant, 1851. Polycanoninae Lesne, 1896 includes 2 genera from Asia and North America. Psoinae Blanchard, 1851 includes 2 tribes; Chileniini Lesne, 1921 with several species of Chilenius Lesne, 1921 from Chile, and the widespread Psoini Blanchard, 1851, the largest genus of which, Psoa Herbst, 1797, includes about 10 species and is Holarctic, the type species P. viennensis Herbst, 1797 occurs throughout Europe, although not the U.K., and Asia Minor. Dinoderinae Thomson, C.G., 1863 includes 6 genera and is Holarctic and African, the large genus Dinoderus Stephens, 1830 includes about 125 species. Dysidinae Lesne, 1921 includes 2 genera; the monotypic south-Asian Apoleon Gorham, 1885 and Dysides Perty, 1832 with 2 New World species. Euderiinae Lesne, 1934 includes the single monotypic genus Euderia Broun, 1880 from New Zealand. Lyctinae Billberg, 1820 is cosmopolitan with about 70 species in 12 genera and 2 tribes. The Lyctini Billberg, 1828 includes the cosmopolitan Lyctus Fabricius, 1792 which is the largest genus of the tribe with 25 species, and Minthea Pascoe, 1863. Trogoxylini Lesne, 1921 includes 6 genera and is mostly tropical.
POLYPHAGA Emery, 1886
BOSTRICHOIDEA Latreille, 1802
Some species of several genera e.g. Dinoderus Stephens, 1830 and Lyctus Fabricius, 1792 have adapted to live in stored products and as a result have become cosmopolitan pests. In general species of Bostrichidae are specialized to live in relatively dry dead wood of a wide range of trees as well as bamboo and seeds. The ability to tolerate dry conditions in carbohydrate-rich environments, along with the males producing aggregation pheromones when they find starch-rich products, has allowed them to move from the wild to stored foodstuffs and to attack wooden products, carvings and wickerwork etc. and so some have become serious pests. They are constrained by the larvae being internal feeders and so they must be small enough to develop entirely within an individual seed or scrap of host which will also accommodate the pupa and resulting adult. The larvae will not survive in exposed situations. Thus the cosmopolitan Rhyzopertha dominica (Fabricius, 1792) has become a significant stored grain pest that also infests fruits, seeds and woody parts of about 30 plant species. In general larvae are wood-borers but beyond the well-known pests a few are known from stored grains and tubers and there have been records of Rhyzopertha dominica developing in books. They gain nutrition from the starch within the dead wood etc. that they consume as they tunnel, but some also attack living plant tissue e.g. species of Dinapate, Psoa and Melalgus Dejean, 1833 develop within tree and vine stems and may occasionally become pests; Psoa viennensis attacks vines while Melalgus confertus (LeConte, 1866) is known as the Grape cane borer, or the Olive twig borer. Tropical species are regularly recorded in temperate areas from imported timber etc. and seem to be readily adaptable to other hosts, endosymbiosis involving gut-bacteria is well-documented within the family and allows many species to live and develop within very low moisture environments. Most species are secretive and will need to be looked for at night on fallen timber while some will be found under bark or recorded from extractions of wood debris.
Bostrichidae are a morphologically diverse group, they range from about 1.5 to 50mm in some tropical species although most lie in the range 2-20mm, they are elongate and cylindrical or variously depressed and most are drab brown to black but many species from all regions are variously red or yellow and some have metallic green or blue reflections or markings. The Palaearctic Bostrichus capucinus (Linnaeus, 1758) is a suitably impressive example. As a group they are difficult to define on external morphology because the variation is wide but many are obvious from the convex and ‘hooded’ pronotum, although smaller species may be confused with Scolytines, many even having the elytra concave and laterally toothed at the apex, but they differ by having straight antennae with distinct and free club-segments. Three subfamilies lack the hooded form of pronotum; Psoinae, Polycaoninae and Lyctinae, and some Psoinae are brightly coloured red, yellow or metallic blue and so may be confused with Clerids but they are distinct as the palps are not expanded. These groups generally may be confused with the Colydiidae but they all have the tarsi 5-segmented. In some sense the family might be characterized by the type genus Bostrichus Geoffroy, 1762 and especially so by B. capucinus, the so-called Capuchin beetle, but it also includes some distinct forms; species of Lyctinae have variously been included in a range of other families such as Colydiidae, Ciidae, Cryptophagidae and Ptinidae etc. and many earlier authors regarded it as a distinct family. The monogeneric Endecatomidae LeConte, 1861 has sometimes been included as a distinct group within the present family. The Chileniini Lesne, 1921 (Psoinae) was originally a distinct subfamily including the single genus Chilenius. The single species of the Euderiinae includes a combination of features not otherwise seen in the family e.g. an antennal groove between the anterior coxae and long metatrocanters, and it was originally placed in the Ptinidae.
Many species are glabrous or nearly so but the flattened Lyctinae forms are distinctly pubescent throughout, with coarse setae to the forebody which are arranged in rows or patterns, and fine pubescence to the elytra which form rows along the striae. Some have dense scale-like pubescence which may form a distinct symmetrical
Psoa viennensis Herbst, 1797 is a significant pest in many Mediterranean countries.
pattern e.g. Lichenophanes Lesne, 1899. Head generally not visible from above; recessed into the thorax and hypognathous, in some groups e.g. Lyctinae, prognathous and exposed from above. Pubescence variable; many glabrous to only very finely so but there are some spectacular exceptions e.g. Lichenophanes bicornis (Weber, 1801) or Xylomedes rufocoronata (Fairmaire, 1892) which has layers of very long and dense yellow hairs bordering the inside of the eyes. Eyes convex and protruding; oval or round, and usually small but sometimes relatively large e.g. in species of Scrobicia Lesne, 1901. Vertex and frons very variable, often strongly convex and sculptured, in Lyctinae almost flat, labrum transverse and small, partly covering the robust and curved mandibles which may be simply pointed or bifid. Palps small and slender, without expanded apical segments; maxillary palpi 4-segmented, labial palpi 3-segmented. Antennae inserted laterally in front of the eyes and over the base of the mandibles, beneath a variously expanded lateral margin, 10 or 11-segmented and straight, never geniculate as seen in many Scolytines, generally with 2 large basal segments, transverse intermediate segments and a 2-4 segmented club, the segments not fused as in Scolytines, club segments vary from quadrate and rounded to transverse, sometimes strongly so and, rarely, lamellate or flabellate e.g. in Euderia. Pronotum very variable, flattened and quadrate or nearly so in Lyctus etc., otherwise strongly convex and produced over the head, rounded anteriorly and with distinct posterior angles which are sometimes produced, roughly sculptured; rasp-like or toothed anteriorly, generally as far as or a little beyond the middle, in some with horns developed anteriorly e.g. in the Neotropical Apates fortis (LeConte, 1866), sometimes splendidly so e.g. in Bostrychoplites Lesne, 1899, an African genus of about 15 species. Generally without borders although these are variously developed, sometimes only towards the base, in Lyctinae and some Xyloperthini where they may be simple or denticulate. Prosternum relatively long in front of procoxal cavities that may be open or closed posteriorly, the process very variable from wide to narrow or absent. Mesosternum generally narrow and short, the coxal cavities round, contiguous or narrowly separated, metasternum broad and usually very long and flattened, the coxal cavities oval or transverse, usually almost touching but widely separated in Lyctus. Scutellum exposed and usually small; triangular to quadrate or oval. Elytra very variable; short, almost quadrate in e.g. Sinoxylon ceratoniae (Linnaeus, 1758), to elongate and sometimes very elongate, usually with prominent shoulders and coarse punctation which may be random, as in some Neoterius Lesne, 1899, or distinctly striate, many have longitudinal carinae or other dorsal sculpture, the apex is often convex and simply rounded e.g. in Dinoderus minutus (Fabricius, 1775) while in many there is a distinct apical declivity or concavity, often with lateral teeth or hooks. Sometimes they are extremely developed e.g. in some African Xylion Lesne, 1901 (Xyloperthini), here they are cylindrical and almost smooth; lacking striae and only finely punctured, and produced apically into a series of horns, the anterior of which is very long and incurved, hook-like and heavily sclerotized. Epipleura variously developed, generally narrow or obscure in the convex species, well-developed and often wide towards the base in Lyctus etc. Wings fully-developed in most species. Abdomen with 5 free ventrites or, rarely, 6 when the basal segment is exposed. Legs relatively long and usually slender, trocanters small and generally hidden, procoxae small and weakly projecting, meso- and metacoxae weakly projecting, if at all, trocanter attachment to the femora oblique or straight. Femora generally slender and unadorned, tibiae slender and without teeth, each with a single apical spur. Tarsi 5-segemented or rarely, in Psoa, 4-segmented, the segments slender and without lobes, the basal segment often very small.
Fully-grown larvae are 3-20mm in length (up to 60mm in some tropical groups), crescent-shaped, glabrous or with a few scattered setae or, rarely, with dense, fine and short pubescence, and dull creamy to white. Head elongate and flattened, or globular, usually retracted into the thorax, and with 2- or 3-segmented antennae. Clypeus and labrum distinct, mandibles symmetrical, strongly curved and with or without an internal tooth. Maxillary palpi 2- or 3-segmented, labial palpi 1- or 2-segmented. Thorax enlarged, meso- and metathorax sometimes with lateral folds, in Bostrichinae the prothorax has an oblique longitudinal structure within the tissue above the spiracle. Legs 5-segmented. Abdomen 10-segmented, each with up to 3 lateral folds, apical segments enlarged but not modified.
The U.K. list includes 5 species in 4 genera and 3 subfamilies. Lyctus brunneus (Stephens, 1830) is widespread though local across southern and central England but appears to be absent in the west. Our other species, L. linearis (Goeze, 1777) has a similar distribution but is much more local and rare, both may be found when working dry decaying fallen timber in woodland and parkland etc. or looked for at night when they are active on the surface of timber that has been stripped of bark. Our remaining species are known from only very few scattered records, generally from accidental imports, Bostrichus capucinus (Linnaeus, 1758) (Bostrichinae), Rhyzopertha dominica (Fabricius, 1792) and Stephanopachys substriatus (Paykull, 1800) (both Dinoderinae).
As well as these five species a number of others are listed as non-established introductions to the UK:
Amphicerus cornutus (Pallas)
Apate monachus (Fabricius)
Bostrychoplites cornutus (Olivier)
Bostrychus jesuita Fabricius
Dinoderus bifoveolatus (Wollaston)
Dinoderus brevis Horn
Dinoderus distinctus Lesne
Dinoderus ocellaris Stephens
Heterobostrychus aequalis (Waterhouse)
Heterobostrychus brunneus (Murray)
Heterobostrychus hamatipennis (Lesne)
Lyctoxylon dentata Pascoe
Lyctoxylon japonicum Reitter
Lyctus africanus Lesne
Lyctus cavicollis LeConte
Lyctus discedens Blackburn
Lyctus planicollis LeConte
Lyctus simplex Reitter
Lyctus sinensis Lesne
Micrapate xyloperthoides (Jacquelin du Val)
Minthea rugicollis Walker
Octodesmus parvulus Lesne
Phonopate stridula Lesne
Scobicia declivis LeConte
Scobicia pustulata (Fabricius)
Sinoxylon anale Lesne
Sinoxylon conigerum Gerstaecker
Sinoxylon crassum Lesne
Sinoxylon doliolum Lesne
Sinoxylon pugnax Lesne
Sinoxylon ruficorne Fåhraeus
Tetrapriocera longicornis (Olivier)
Tristaria grouvellei Reitter
Trogoxylon impressum (Comolli)
Trogoxylon parallelopipedum (Melsheimer)
Xylion adusta Fåhraeus
Xylion collaris (Erichson)
Xylion cylindricus (MacLeay)
Xylion securifer Lesne
Xylobiops basilaris (Say)
Xylodeleis obsipa (Germar)
Xyloperthella crinitarsis (Imhoff)
Xyloperthella picea (Olivier)
Xylothrips flavipes (Illiger)