Natural History

Back to natural history menu click here


Here follows a list of insects that are fairly prevalent in mountain areas in Eryri. Their presence is not guaranteed, weather conditions drought, wind etc. can have a big part to play on whether they are seen.

Dragonflies are quite frequent in both lowland and moorland habitats, the big golden-ringed dragon-fly being the most noticeable upland species.

Beetles may look to be a difficult study; with nearly 4,000 species in Britain alone. A conspicuous beetle in early spring is the bright green tiger which flies along in short spurts just in front of you as you walk along the hill tracks. Then in early summer, the a little smaller than a cockchafer is a smaller chaffer, the June Bug. It hatches out of the turf in vast numbers, only to be gorged upon by a variety of birds. It is reddish in the body with a metallic green head. Click beetles too are very frequent in some years in the mountain pastures. In contrast, the amazing beetle, the glow-worm is only locally frequent in the valleys.


Large bumble-bees appear very early on high ground as soon as winter is over; and in summer wild bees of various kinds are abundant in the hills, especially in the heather bloom.

The largest ants, the Wood Ant, which makes huge piled-up rests, is found in many lowland and semi-upland woodlands of Eryri, in particular the northern and western areas.

Flying Ants, usually in August, attract spectacular, acrobatic flights of other birds.The Giant Wood Wasp (Sirex gigas) is still seen in Eryri; the drone of its massive wings forewarning of its presence, it is quite harmless though. It is preyed on by the large Ichneumon Fly.

Crane-flies, or daddy-longlegs, especially smaller species, can be seen hatching in great numbers in the moorland turf in spring and summer.



A rather large, sluggish, black fly is conspicuous in August, especially on wet heather moors.

This fly (Bibio ponamae) is often seen in great numbers crawling over the heather, and being a weak flier, often gets blown on to the surface of lakes and is often eaten by the fish.

Horseflies are at their worst in July. The commonest and most insidious is the small grey species, Haematopota pluvialis.

Also profuse and most determined is the mottle-winged species with extra-brilliant green eyes, Chrysops caecutiens.

The huge Tabanus sudeticus, with a nearly two-inch wingspan is thankfully much slower to settle and bite than the others and is more easily beaten off.

Many of these particular beasts are found quite high on the mountains, so beware