WE'VE not had much in the way of summer so far this year and already there are signs of autumn on the horizon.

Soon, now the swifts will be off on their long journey to the wide African Velt.

If the number of birds at Tring reservoirs is any judge of the success of the breeding season this year - then the swifts have done well. Large screaming parties of young hurtle through the evening air.

Swifts are at their most active just before the bats come out and huge numbers of insects emerge from pupae on the water's surface.

The emerging adult gnats dry their wings and fly up to join the others - rising like a cloud of smoke over the hedges and bushes that surround any body of unpolluted still water.

They don't like the wind because it will blow them away from their intended mates in the nuptial dance.

I used to fly single engine planes a few years ago and I know only too well that the best time to fly for sheer pleasure is at the end of the day.

The air is settling and thermal activity, caused by the sun warming the ground, lessens in the cool of the evening.

The moisture content of the air is higher in the evening too and the air itself slightly more dense than during the day.

In summer, this creates perfect flying conditions. Insects, with hundreds of millions of years of experience in the art of flight, are fully aware of these benefits.

Swifts also know when the gnats are out and about and gather to feast on them before flying up into the upper air stream to sleep on the wing - cruising on the winds that blow constantly above 2,000ft.

This is not the jet stream that blows in excess of 100 miles an hour at an altitude of 20,000ft and speeds the journeys of transatlantic human air travellers - it is a more gentle breeze of about 20 to 30 miles an hour.

Swifts are masterful fliers, but they're not into extreme high level flight. Their long wings are designed to cut through dense air at high speed.

They also have an unusual ability to sense the onset of a thunderstorm or a weather front long before the effects are seen by ground-based humans.

Swallows and martins too have this skill, but swifts seem to be better at it - sensing a thunderstorm from nearly 100 miles away.

As if responding to some hidden signal, all the swifts in an area will rush to the storm front. The weather conditions that create thunder storms are complex. The entire event is accompanied by great movements of air in front of the storm.

Warm currents are drawn skyward with enormous power drawing insects up to great heights where they are stunned by the cold upper air and speedily harvested by the swifts.

We see only the electrical activity and hear only the explosive crash as immense electric sparks fly. If you're close to a storm, the turbulence can be frightening, but swifts revel in their mastery of flight and to them the swirling insect filled air is a banquet.

Their long scythe shaped wings are perfectly streamlined and powerful muscles allow them to fly the storm front with impunity, rising and falling in the turbulence with no ill effects.

The young swifts reared in our area will have to learn to anticipate weather fronts as they head across Europe towards Africa in a mammoth journey that will keep them in the air for a period of two years before they will return as breeding adults and a brief respite from flying.

Swifts can live for more than ten years - a considerable age for a relatively small bird. A swift on the ground will usually be a young recently fledged bird come to grief on its first flight, or sick, or injured.

They do sometimes fly into a pond or lake as they chase food, or dip to drink (although this is rare). Their only predator is the beautiful hobby falcon.

There has been a great deal of wet weather this year. On the one hand this seems to have benefited the moths, but on the other hand it's not been such good news for most of the butterflies. Our garden buddleia came and went with the minimum number of peacock and small tortoiseshell butterflies and I'm waiting eagerly for the sedum flowers and michaelmas daisies to open to see what comes, if anything, for a late drink of nectar.

Moths have had the best of it probably because they are better able to survive the vagaries of a wet summer. Being creatures of the night they don't need the sun to kick their metabolism into gear - although, it must be said some of the day flying moths have also enjoyed a good year.

I've had reports that the hawk moths have produced large numbers of eggs and their big, showy caterpillars have safely pupated. As the days begin, almost imperceptibly, to grow shorter they are hatching into the largest, most beautiful, fastest flying of our native moths.

If the weather is right they will be joined by immigrant hawk moths from the near continent and some of these foreign hawk moths are spectacular.

Hawk moths are so called because of their shape (long winged and streamlined) rather than for any tendency to hunt other creatures.

They feed on nectar. Many are highly specialised and each individual species is confined to feeding and laying eggs on one particular species of plant and can be badly affected by sprays that we use on our gardens and field crops.

It's hard to say where's the best place to look for hawk moths and their larvae - other than the elephant hawk moth which lays its eggs and rears its big, snake like caterpillar on rosebay willow herb and great hairy willow herb.

I love to see them. The caterpillar may be big and ugly, but the adult moth is a beauty.

Green and red, cream and brown in colour, the overall impression is of a rosy red insect with a two-inch wing span.

They emerge throughout July and August and, to me, typify the lazy days of late summer.

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.