Keeping tabs on tiny aliens

This is daddy-long-legs time, all crooked knees and elbows. They scribble on the windows, leave wings to glint in spiders' webs at the corner of the pane. Rattling at a lamp, they call for rescue in cupped hands, as if one didn't know that cranefly young are miserable leather jackets, root-chewers all.

The house is a lot less permeable to wildlife than it once was, most of the throughways for slugs, beetles, devil's coach-horses, having been stopped up. A front door left open in summer is an invitation: a wren dropped in not long ago to creep along the bookshelves for spiders, and a robin arriving in the kitchen could have done well on silverfish. Neither, I hope, alarmed the weevil that lives somewhere around my desk and pokes its nose out to say hello on just one morning each spring.

Houses generally are becoming far less nature-friendly, even to species that have grown up, so to speak, with people. Swifts are fast running out of nesting-places, as old roofs are replaced; house-martins have similar problems, trying to stick mud to gable walls freshly coated with slippery paint.

Insects, as I say, are finding fewer entrances, as cracks and crevices are closed, and fewer corners in which to dodge the vacuum-cleaner. But as our native species are closed out (some useful predators among them), trade and travel are bringing fresh aliens indoors, some to prove quite unpleasant pests.

They are itemised among the sometimes fearsome exhibits in Irish Indoor Insects: A Popular Guide (Town House, £16.99). The book was undertaken as a hobby by Dr Jim O'Connor, keeper and entomologist at the Natural History Museum, and a freelance entomologist, Dr Patrick Ashe; they have worked together for years in identifying insects for the public.

The two men love their subject and lament the near-entomophobia that still inhibits the closer look at six-legged things. But even they cannot admire, say, the urinal fly ("an obnoxious creature"), and Sean Milne's meticulous drawings of lice, bugs and cockroaches are sometimes matched by gruesome details of the sort that forensic pathologists show such relish for on television.

Do we need to know, for example, of the sheep-maggot fly's attraction to the anus of ailing humans? Or that the tropical and minute Pharaoh's ant, already well established in Ireland, is among the potential hazards of hospital, given as it is to wandering from one wound to another - a habit already noted in the brown-banded cockroach, from India, which has turned up in the doctors' homes of two hospitals in Northern Ireland?

The answer, of course, must be yes, for the book is meant to help health professionals, food manufacturers, restaurant owners, as well as the general reader. We may be intrigued to hear that there is a confused flour beetle and a depressed flour beetle as well as more ordinary-sounding ones, but for granaries and flour mills these are just two of a whole platoon of troublesome pests.

Imported indoor insects seem to be as old as international travel. The house cricket, for example, possibly arrived in these islands with returning crusaders in the 13th century. I had never heard the cricket's chirp (made by the male rubbing its forewings together) until coming to live in Connacht and rekindling the fire on a hearth that had been cold for 20 years.

For more than 30 years from 1960, there was no confirmed record of a cricket in Ireland and some entomologists thought it was extinct. Then one jumped out of a fireplace of a fairly new house in Castleknock, the owners of which have been happy to conserve the colony.

The new book does not consider spiders, which are not, of course, insects, but arachnids, with eight legs and a different body structure. It misses, therefore, some of the dramatic confrontations with creatures that climb out of crates from foreign parts.

The ubiquitous American cockroach arrives in rubber from Malaysia, bananas from Columbia and newspapers from India. It had a notable effect when discovered, in some numbers, in a container of cotton from West Africa opened in Co Offaly. "The workers panicked and refused to work until the infestation was eliminated."

More reasonable, perhaps, is the alarm sometimes caused by one of Ireland's largest buzzing insects - the giant "wood wasp", ringed in black and yellow, that isn't a wasp at all. The book cites reports of "families in the Wicklow mountains running for their lives, after mating swarms of giant wood wasps had congregated on picnic sites" - the fright gaining force because the female's long ovipositor can look so much like a sting.

In fact, she uses it to drill holes for her eggs in the living wood of conifers, and when fresh-sawn wood is rushed into use (in pallets, say, or deal panelling), the grubs can hatch out indoors, thus earning Urocerus gigas a page to itself.

A householder's panic can be a boon to cowboy "pest control" firms. Among the big insects most frequently submitted to Dr Jim O'Connor for identification is the ordinary woodland maybug, or cockchafer, which is often attracted indoors by lights. A woman who found some in her house assumed they were emerging from the woodwork and paid a straight-faced operator several hundred pounds for a totally unnecessary spraying.

At its most extreme, paranoia about insect infestation can become a persistent psychological syndrome called delusory parasitosis. It is summarised in some detail in the book for the benefit of professional eradicators, health inspectors and medical personnel who may find themselves trying to deal with a distressing and intractable condition.

On the other hand, the problem could be real. The authors quote the bizarre episode of a Dublin woman complaining about crabs in her house - not the irritating pubic lice the French call papillon d'amour, but the salty, marine sort. She lived in a street 3.5 km from the sea - but a tidal underground river connecting to drains had, indeed, provided her visitors.