Suomen Luonto
English summaries 9/2001

Observations at a butterfly bar; nocturnal moths at alcoholic bait
By Leigh Plester and Juha Valste; Hannu Aarnio
Pages 2426

One can establish a \"bar\" for insects in the early autumn which will be appreciated in particular by some butterflies, moths and wasps. As an attractant one can use natural produce like overripe fruit. A popular brew, too, is a mixture of beer and sugar which is encouraged to ferment by the addition of yeast. Insects are attracted by fermentation products, especially alcohols and esters.

For serving guests who fly in for a drink, one can use a saucer or similar receptacle, which is placed on an outdoor table. The bait can be also be offered in a more natural way, by spraying it on to tree trunks, for example. One successful method used by veteran butterfly collectors is to saturate pieces of sponge rubber or polyether foam, which are then hung on trees and bushes.

On a sunny autumn day, business at the bar can be brisk. The intoxicating brew may be visited by a number of nymphalid butterflies, including Camberwell beauties, red admirals, small tortoiseshells and commas. At night, large moths like the red underwing and the Clifton nonpareil may well be attracted to the bait, along with a contingent of noctuids and lasiocampids. The Clifton nonpareil competes with some Finnish butterflies for the title of the largest Lepidoptera species in the country. In Finland, butterflies may still be active on warm days as late as October. Tanking up on sugars, alcohols and esters is a sensible undertaking for butterflies which are preparing for long hibernation in the adult stage.

In the wild the most attractive places for insects with a taste for alcohol are rowans, with their clusters of red berries, and apple trees. Overripe berries and fruit which have had the frost on them are full of sugar and alcohols from the latterís fermentation. Aside from butterflies and moths, these are also attractive to birds like waxwings and fieldfares.

Delaware Bay, a stop-over for waders
By Pertti Ranta, Ari Lavinto and Jouko Sipari
Pages 4044

Delaware Bay is located in New Jersey, on the USA\'s east coast. For a couple of hectic weeks towards the end of May, the bay forms a resting place for migrants and a meeting point for waders and horseshoe crabs (also widely known as king crabs). These birds are passage migrants on their way from South America and the shores of the Bay of Mexico to their arctic breeding grounds. They follow the contour of the east coast of America, which offers the birds a large number of resting places. Delaware Bay is unique, however; it is situated at the halfway point on the thousands of kilometres long migration route and it also offers the visiting birds easily accessible food.

Horseshoe crabs (more closely related to spiders and scorpions than to actual crabs) come up into the shallow waters of the Delaware Bay from mid-May onwards. At the end of the month there are many ovipositing females. Each of them lays over 20,000 eggs a couple of millimetres in diameter. And, as each female lays a batch three or four times during the month of May, 80,000-90,000 eggs are deposited by every individual ëmotherí. Added together, there may be half a million horseshoe crab eggs per square metre! These hatch after around a month.

Waders arriving in the bay, hungry from their long flight, have a feast of eggs ready for consumption. At the end of May and beginning of June 1.5 million waders briefly settle in the bay which in the space of a fortnight gorge themselves on horseshoe crab eggs bursting with nutritious substances. This surfeit of food results in the wadersí weight doubling before they set off again for the distant tundra.

The birds found most abundantly in the Delaware Bay are the red knot, ruddy turnstone, sanderling, semipalmated sandpiper, dunlin and dowitcher, with a sprinkling of western sandpiper, grey plover, semipalmated plover and willet.

The unappreciated beauty of the much-maligned mire
By Matti Torkkomäki
Pages 411

Many Finnish prejudices prevent citizens from appreciating the beauty of Finland\'s mires and bogs. To the ancestors of today\'s Finns any bog or mire was an annoying obstacle, a recipe for crop-destroying frost, and a place where evil lurked. This accounts for the fact that there are many negative references to this type of habitat in the Finnish language. Modern science is able to describe bogs and mires better than myths, but science and the human mind remain in totally different worlds. The roots of legends are too far away to be instantly cut.

A bog is a land of extremes: some of Finland\'s most magnificent birds and exotic plants choose to live on acid, poor and barren bogs. Many common bog plants even are extremely lovely. Wildlife photographer Matti Torkkomäki discovered the beauty of Torronsuo at Tammela. This so-called raised bog has a surface area of 2500 hectares and was made into a national park in 1990. For Torkkomäki a bog or mire is a powerful aesthetic experience. In its details it is overwhelmingly attractive and ever-changing, its pallet of colours simply unbelievable.

Lord of The Ants ; The hexapod cattle herder
By Juha Kauppinen; Jouni Sorvari
Pages 3034

Ants form an important work force in the forest community. However, few people bother to study them in Finland. The work of ant-expert Jouni Sorvari started off as a hobby. As a child he became fascinated by the antics of ants in the back yard; now he is studying the effect of clearfelling on the nesting success of wood ants, as well as the problem of classifying species and the distribution of these in Finland.

Sorvari is intrigued by the social structure and behaviour of ants, particularly cooperation between individuals. Their extreme ecological significance also gives food for thought.

Many species of ants herd aphids as people herd cattle. They \\\"milk\\\" honeydew from these and also use the aphids in the same way as we use beef cattle. Large aphid herds slow down the growth of trees but, from the forestry angle these herds live in over-aged trees. The efficient way in which ants prey on insects affects insectivorous birds, while the ants also have an impact on the insect and spider faunas in the neighbourhood of their nest.

A lot of attention has also been devoted to the effect of ants as destroyers of pests. Many animals eat ants, but their greatest enemy is other ants. Ants compete with each other for food and territories. They are also good indicators of environmental change. For instance, the effect of modern, efficient forestry is apparent in the relative proportions of different species of ants in the forests.

Teksti: Leigh Plester