A sinister stalker in the matt black of a biker's leathers

ANOTHER LIFE:AN ERROR OF TIMING the other morning found me at the bottom of the boreen but still severed from the strand by the deep and brimming conjunction of river and spring tide in the channel behind the dunes.

It’s a misjudgment that, in reverse as it were, sometimes leaves the odd and errant summer 4x4 sequestered on the far side, its occupants clustered at the water’s edge in drooping disbelief: they can be left there for hours.

It was one of the quiet, pearly days of the month, not a stir in the feathery reeds along the ditch, not a murmur of traffic from the whole wide scarp of the hillside. A dilatory wheatear, pausing on a fence post, had long resumed its flight south. I turned to walk my wellingtons home again. Then the single other locus of movement on the boreen brought me to a halt. A beetle was crossing the road ahead of me.

My ageing eyesight tabbed it at once as a deargadaol, the devil's coach-horse, Ocypus(sometimes Staphylinus) olens. Where most ground beetles are glossily black – sometimes quite prettily so, with a violet sheen – the deargadaol wears the sinister matt black of a biker's leathers, the better to stalk other insects at night. As if in laddish confirmation, this one cocked its tail briefly, scorpionlike, as it trundled into the light.

It proceeded in a straight line, and at a steady speed, from one ditch to the other, before disappearing, unhurriedly, into the grass. Why, I had to wonder, did this generally nocturnal, constantly hungry and predatory creature, sheltering usually during the day under stones, logs or leaf litter, set out to cross some four metres of daylit, gravelly road quite bare of worms or woodlice?

Once home, I embarked on scientific preliminaries. “Why beetle cross road?” I inquired of Google (as one does). It offered 28,400,000 discussions of the topic, all but a few of which referred to a misspelled multiple, The Beatles, and the zebra crossing outside Abbey Road Studios, in London.

This crossing appeared on the sleeve of the last album they recorded at those studios and has become a sort of shrine to the lads in their prime. Seduced to a live webcam of the scene, I found it, after 42 years, still drawing Sunday-morning teenage fans to pose on its stripes for photographs, much to the annoyance of the city’s taxi drivers.

Yes, well, otherwise . . . a few nice items on dung beetles, which, in a hurry to get their quite sizeable balls of dung safely away from a cowpat, may push them across a road – this, I was intrigued to see from the pictures, with their hind legs raised, which must take some doing.

But there was also, as first choice – such can be the splendid serendipity of Google – a brilliantly funny little film on YouTube. Made in the United States by Jan Skrentny in 1985, and the delight of many festivals, it offers a beetle’s-eye view of the perils of crossing a road while singing under one’s breath and dodging bicycle wheels, joggers and a malicious small boy with a table fork.

Thus delighted, I switched to Google Scholar for the heavy stuff.

But while scientists are great explorers of the what and how of insects, the why of the creatures’ behaviour can easily disappear within the nerve-driven actions and reactions we call instincts. Self-preservation demands ultrarapid response, but here was a beetle boldly going into increased risk from, say, a watchful kestrel.

Even for rove beetles, as the deargadaol’s family are known, this seemed many multiples of six steps too far (and, yes, it could have flown, just about, but the wings beneath the elytra are rarely used). Its straight-line progress towards the sun, even one hazed by cloud, was, however, typical of the sun-compass behaviour of many insects. (Some Italian shore-dwelling beetles use it to steer them away from the tide.)

As four metres of road were unlikely to offer much food, what about that other imperative, reproduction? In Skrentny's film, such a motive is finally played out to the strains of Some Enchanted Evening,and, yes, the autumn is mating time for the devil's coach-horse.

Pheromones, then. The female deargadaol does, indeed, have a distinctive mix of volatile hydrocarbon compounds on its skin. But while laboratory study has male beetles exploring females with their antennae prior to mating, I have yet to find any suggestion that the female scent can be borne on the air in the manner, say, of moth pheromones, which can draw a male from 50km away. Indeed, the general failure of beetles to cross roads is widely blamed by ecologists for preventing a healthful flow of genes between the populations on either side.

My deargadaol, after all, may just have been roving hopefully.

Eye on nature

I had a visit from a dragonfly at my market stall in Marlay Park on September 24th. Was it a golden-ringed dragonfly? - Deborah Webb, Rathfarnham, Dublin 14

From the photograph you enclose, it was a female autumn hawker (Aeshna mixta), a dragonfly new to Ireland. It was first seen in Wexford in 2000 and has since spread along the south and east coasts. It is a small dragonfly and the latest to emerge each year, on the wing from late July until late October.

Looking out of my window, I saw a most exotic bird, a juvenile peregrine, disembowelling a blackbird in my tiny garden. It looked me in the eye as it boldly plucked and ate, and when the carcass seemed light enough it flew away with it. It seemed to frighten all the birds, because no bird came to my garden until six days later. - Josephine Russell, Clontarf, Dublin 3

Today at Farmleigh I saw a squirrel running along the grass with a dead squirrel in its mouth. Was it going to eat it? - Joseph Fagan, Castleknock, Dublin 15

Grey squirrels are known to be cannibalistic. I’ve found no report of such activity by the reds, but they are known to eat birds.

* Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo, or e-mail viney@anu.ie. Please include a postal address