Most of the beetles in this group are characterised by long antennae and a cylindrical body shape, but there are exceptions. If you are uncertain if a beetle is a true long horn look at the second antennal segment. In true Cerambycids (longhorns) this segment is smaller than the others.
There is a national recording scheme that has both a facebook page and a twitter account ran by both the Lord of Longhorns Wil Heeney and the Lady of longhorns Katy Potts. So if something interesting lands in your trap, ensure you record your sightings.
Fancy a Key? Try one of Mikes HERE
Two spikes at the rear of the elytra
There are two other similar species
P. hispidulus: Also has 2 spikes at the rear but has white scutellum 6.0-70 mm
P.fasciculatus: has no spikes at the rear 5.0-8.0 mm
evenly curved sides to the pronotum
Covered in dull grey hair (pubescence)
Hind tarsomere 3 incised deeply (pictured right)
Looks very similiar however hind tarsomere 3 is not as deeply incised as that of A. rusticus (pictured right) and has no hairs on the eyes. 9.0-27.0 mm
An absolute stonker of a beetle, which is difficult to mix with any other species. Eggs are laid in crevices of bark and develop for at least 3 years feeding on the rotting wood.
Spiked edges on pronotum
Serrated antennae (more so in males)
Dark brown to black
Two beetles for the price of one! This species comes in two colour forms, a metallic blue/green with a red pronotum or a paler brown with an orange pronotum, head and appendages
rounded sides to pronotum
rectangular shaped elytra
The first tarsomere on the hind leg is longer than the total length of the 2nd and third (separating it from Poecilium lividium)
All year round
The odd one out
Large boggled eyes
Chestnut brown elytra
Black head, pronotum and appendages
June - ?
Superficially resembles the other tenebrionids Lagria hirta and Isomira murina
Tenebrionidae - its all in the cheeks
Tenebrionidae are very varied in appearence and it can be a pain to separate them from very similar looking beetles. In most instances they can be split by looking at the Gena, effectively the cheeks of the beetle. In Tenebrionidae the gena protrude across the front of the eye, giving them almost cartoon like cheek features. It certainly works for splitting Nalassus from other UK Carabidae.
Typical Tenebrionid head showing expanded genae marked in red via: Wikicommons