Rannoch Net

Peter Orton wrote the following article for the 'Rannoch Record' in 1964

When the entomologist talks of Rannoch then you can be sure that he has the Black Wood in mind. This is because this remnant of the old Caledonian Forest has an abundance of insects, including some striking species which are particularly associated with Scots Pine.

When the first warm spell comes in May, many of these insects start to emerge from their winter hiding places, either as adult insects, pupae, or larvae. If, as happened this year, this warm spell comes late, then many species emerge together and the air seems to be full of flying insects. These include beetles, flies, sawifies, ichneumon-flies, bumble-bees and wasps. The moths tend to come later and the dragon-flies appear in late June or early July.
A number of beetles are only seen in their adult form during this brief period of a fortnight or less. These include the Timberman, easily recognised by its very long antennae, whose larvae live in pine logs and stumps. Rannoch is one of the few places where native specimens of this Longhorn beetle can be seen. It is not very common and has the advantage of being well camouflaged, so it is easily overlooked. When the sawmill was in operation it was possible to find six or more males at one time sitting on the sawn planks sunning themselves. Now one is lucky to see one or two specimens in any one year. There are a few other types of Long-horns which emerge at this time of year and often attract attention, but they seem to have a longer life span and can be seen until late June.
The Birch Sawfly, a large black creature with clubbed antennae and four transparent wings, emerges at this time too and often attracts attention. This is not confined to areas such as Rannoch for it lives on birch, but, nevertheless, it is an important feature in Rannoch insect life. Later in June or in early July the large Horntail, or Wood-wasp emerges. This is not a wasp at all, but another' sawfly, that is to say it has four transparent wings, but its body is not constricted into a waist as in a bee or wasp or ant. It is quite harmless but is often the cause of consternation because it is mistaken for a hornet, or a kind of super-wasp, because of its brown and yellow markings. There is also a sinister looking pro-jection at the back end of the female. This, in fact, is not a weapon but an ovipositor with which she lays her eggs in pine logs where the larvae live on the wood, just as those of the Timberrnan do.
The other important class of insect at Rannoch is the black and red Ichneumon-fly. These leggy creatures are two or three inches long, and, having a "waisted" body and four transparent wings, belong to the same group as the ants, bees and wasps. If one is very lucky one may see the female crawling over a pine log, tapping it with her antennae, searching by some unknown means for the larva of the Wood-wasp. If she senses that one is present in the log she will bend her abdomen and push her ovipositor into the wood. When the ovipositor reaches the larvae or their burrow, she will lay an egg and then slowly and with difficulty withdraw the ovipositor. When the egg hatches, the larva penetrates the body of the Wood-wasp larva and slowly eats it. The male of the Ichneumon-fly is similarly coloured but, of course, does not have an ovipositor, and for some reason is much more rarely seen.
Space forbids the inclusion of further examples, but Rannoch has long been a famous collecting ground for insects, moths and beetles, records showing that many species were first identified here as long ago as 1855 when the science of entomology was still in its infancy.



Natural History

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