PYROCHROIDAE Latreille, 1806
The striking colour and large size make these beetles unmistakable, two are widespread and frequently seen in parks and woodland.
Suborder: POLYPHAGA Emery, 1886
Superfamily: TENEBRIONOIDEA Latreille, 1802
Around the World
This small family contains about 150 species included in 32 genera and 5 subfamilies although the limits are by no means certain and the subfamilies Pedilinae with about 50 species, and Agnathinae, with both Palaearctic and Nearctic species, are sometimes considered to be separate families or included within the Anthicidae. Eight species in 3 genera occur in Europe of which 3 extend to the U.K. Adults typically inhabit deciduous woodland margins and parkland etc. where they may be found on flowers, nettles, logs and trunks etc. They are often seen basking on leaves or timber. In the Nearctic region, which hosts 50 species in 7 genera, light trapping, flight interception trapping and even pitfall trapping are productive methods of sampling adults. They are sometimes quoted as feeding on other insects, and this may be the case, but many species are known to feed on plant sap, honeydew and pollen. Adults of Neopyrochroa Blair, 1914 and Schizotus Newman, 1838 are cantharidiphilous, seeking Meloids to consume their cantharidin. Male Schizotus pectinicornis (Linnaeus, 1758) acquire dietary cantharidin in an unknown way and transfer it to the female during copulation, the female then transfer it to the eggshells. The American species Neopyrochroa flabellata (Fabricius, 1787) uses cantharidin during courtship, with the male acquiring dietary cantharidin and advertising this fact to the female during courtship displays. A frontal interocular cleft is used to display the chemical which, via secretions from a cephalic gland, is laced with previously ingested cantharidin. Females are able to gauge male quality by sampling from this cleft and, if they deem the male suitable, receive a large supply of cantharidin as part of his spermatophore. If they accept the mate they distribute the chemical to their eggs which then become significantly protected from attack. Our three large and impressive U.K. species are hardly representative of the family as a whole, the colouration of many species is a combination of red and black but many are dark overall while many have dark elytra with pale macula. The larvae of most species develop among frass under the bark of dead or damaged deciduous wood, often appearing in numbers which represent all stages of development. They are reportedly predatory, feeding on other saproxylic insects and their larvae, but the majority of species are primarily fungivores. Our three large and impressive U.K. species are hardly representative of the family as a whole, the colouration of many species is a combination of red and black but many are dark overall while many have dark elytra with pale macula.
The following general description applies to the family as a whole, but for the purpose of identifying the U.K. representatives at the family or species level they are so distinctive as to be obvious from the general appearance. In the broad sense of the five subfamilies the adults range from 4 to 20mm in length. They are elongate with long, oval elytra that generally widen towards the apex. The temples are broad before a basal constriction so that most species have a distinct neck. The base of the pronotum is generally much narrower than the elytra across the shoulders and so many species appear waisted. The entire body, including to some extent the appendages, is soft and the upper surface is finely pubescent giving many species a silky appearance. The robust antennae are 11-segmented and variable in form; filiform, pectinate or serrate and inserted in front of the eyes and laterally into tubercles. The elytra are generally smooth, finely punctured and shiny under the pubescence, and lack striae. The abdomen has five visible sternites in the female and six in the male. All the tibiae have a terminal spur; otherwise the legs are without spines or teeth. The tarsal formula is always 5-5-4 and the fourth segment is lobed ventrally.
The larvae are distinctive; up to 35mm, yellow or brown and darkened at both ends, parallel sided and flat. The head is strongly sclerotized with well-developed and asymmetrical mandibles. The abdomen is 9-segmented; 1-7 are transverse and lobate, the eighth elongate and the ninth has two prominent urogomphi. Two long hairs project from each segment. The dorsal surface is generally covered with small tubercles.
F. D. Buck
Keys to the UK species of various Tenebrionoidea families. No colour pictures.