Section C
Elateridae– Click Beetles
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These elongate, parallel sided beetles are named after their ability to catapult themselves into the air using a locking mechanism located between their head and thorax. There are 73 species in Britain, however Identification of them all is a bit of a dark art.
If you fancy a go at keying, I recommend a combination of Mark Telfers ‘translated’ Joy Key and Mike Hackston’s Elateridae key.
Update: the new Duff Vol. 3 is brilliant for keying these out, so if you can afford it and want to get serious about Elaterids its a wise investment!
Stenagostus rhombeus
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ID Features
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16-18mm
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A Reddish brown
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Golden pubescence with a darker chevron marking towards the apex of the elytra, this is easier to see in the right light.
Melanotus sp.
There are two of these in the UK, they are big and black and much larger than any other completely black Elaterid species we have.
However, splitting the two is a mammoth task even for the seasoned coleopterist and key features are largely comparative.
There is some discussion between coleopterists as to how accurate these features actually are.
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The below features are from a variety of sources, so I cannot guarantee their validity, but its all the information I have at my disposal. Good Luck!
Melanotus castanipes
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(pictured Left)
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11-20mm
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Has a wider elytral apex
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Shorter antennae
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Elytra 3.8-4.0 times as long as pronotum when measures along the centre line
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May have a greenish/reddish hue
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Melanotus villosus
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11-20mm
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Has a narrower elytral apex
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longer antennae
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Elytra at most 3.5- times as long as pronotum when measures along the centre line
M. castanipes (left) and M.villosus (right) Det. T.James
Agrypnus murinus
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ID Features
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Pronotum transverse (wider than long)
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Antennae short and serrate from 4 onwards
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Mottled appearance (red, grey and silver scales)
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10.0-17.0 mm
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Body black to dark brown
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March- Dec
Athous haemorrhoidalis
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Along with Melanotus, this species is probably one of the most encountered Elaterids in Britain. It is most commonly confused with A. campyloides but is on average much larger and lacks the pale antennae .
ID Features
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Antennae and legs mid to dark brown
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Antennae 11 segmented
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Head and pronotum black
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Reddish brown elytra and pronotal hind angles
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Pronotum moderately punctured but with clear space beteen them
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covered in a fine pale pubescence
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Mid and hind tarsi with 4th tarsomere about a third as long as 3
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All year round
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10.5-15.0mm
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Athous bicolor
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ID Features
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Pronotum dark with lighter edges
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Pronotum widest at its base gradually narrowing towards the head, comparatively straight sides
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Head dark
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Reddish brown elytra and pronotal hind angles
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Pronotum coarsely and closely punctured appearing matt
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covered in a fine pale pubescence
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Mid and hind tarsi with 4th tarsomere about a third as long as 3
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Elytra and legs are generally paler brown to yellow (although darker forms may occur
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Elytra long (2.5 times longer than the length of pronotum)
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May- Sept, Nov-Dec
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8.5-12.0 mm
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The odd one out
Hallomenus binotatus
Family: Tetratomidae
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Associated with bracket fungi and rotting wood in anchient woodland and fens (Duff 2020)
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ID Features
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Pronotum transverse with two basal impressions
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Head short and triangular, often tucked under pronotum
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11 segmented antenna, lacking a club.
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flattened eyes with deep notches
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Narrrow elongate shape
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Dark brown with lighter edes to pronotum and elytra (pictured)
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3.5-6.0 mm
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March to October
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