Insects create soil out of dead plants and animals, they help plants to make seeds and they are food for millions of birds, fish and bats. Therefore, insects are vital for many other species, both plants and animals.
They are also important for humans; in fact we wouldn’t have been able to survive without insects.
However, we know that insects are struggling. Therefore, the national park and Utladalen Protected Landscape are especially important areas for these creepy-crawlies. Here, they can live without being threatened by development and other changes in land use. Many beneficial, important, but also bothersome insects can be found in this area.
Polyommatini (The Blues)
Polyommatini are diurnal and colorful butterflies that visitors easily recognize when hiking in Jotunheimen. Polyommatini can be found on every continent in the world. The majority of them are tropical species, but there are Polyommatini that have adapted their lives to the mountains in Jotunheimen, such as the small blue and the alpine argus.
The small blue is the smallest of all the Norwegian blue butterflies, and it can be found at over 1000 meters above sea level. The small blue is not very common, but numerous examples can be seen in the nutritious grasslands and on scree fields in the mountains, such as at Gjende lake in Jotunheimen.
The alpine argus is only found in the mountains, over 800 meters above sea level. This beautiful butterfly can be spotted on south-facing slopes where there are many flowers.
The Apollo Butterfly
Lucky hikers may get the chance to spot an Apollo butterfly, our largest diurnal butterfly in Jotunheimen. The Apollo butterfly has white, partly transparent wings that are darkly powdered. The Apollos in Jotunheimen are a separate mountain sub-species, and are only found in Norway.
The larvae of the Apollo butterfly feed on roseroot plants, while the adults must have access to plants that produce nectar, such as thistles, star-thistles and field scabious.
The Apollo butterfly became a protected species in 1989. They seem to be surviving in the high mountains, but their numbers are decreasing. Lack of suitable habitat is the greatest threat to this butterfly, which has now received the status of being near-threatened on the Norwegian list of endangered species.
Their dark gray, glistening wings with blood-red spots signal that these moths are not to be eaten. Zygaenid moths actually use hydrocyanic acid as a form of defense against their enemies! They are also very hardy moths and can survive a meeting with a bird’s beak. There are six species of zygaenid moths in Norway, but many of them are rare. Butterflies and moths require open areas with a lot of flowers. Changes in land-use also threaten this species, however, high in the mountains where there are no such threats, the zygaenid moths are managing.
Zygaenid moths are sun-loving insects, and watching these little creatures circling in to land on a flower or a straw is an experience in itself. These moths are only active when the sun is shining, and they are a delight to all mountain hikers who enjoy nice weather in the high mountains! The mountain burnet is the most common zygaenid moth in Jotunheimen.
Argynnini are beautiful, eye-catching butterflies that are often seen when walking through the grasslands in Jotunheimen. They have orange wings with black spots on the upper side.
The small pearl-bordered fritillary and the pearl-bordered fritillary are common in these mountain areas and around the country. It is difficult to distinguish between the two species, and you need to see the underside of their wings to make a correct identification.
The irritating mosquito
What’s the point of the irritating mosquito?
Mosquitoes and midges are important sources of food for fish, birds, bats and other animals.
Especially high in the mountains, swarms of flies and mosquitoes can have an impact on animals that are much larger than themselves. Swarms of insects can determine where the large herds of reindeer graze, migrate and leave behind nourishment in the form of dung. This is how they influence the entire ecosystem, just like a ripple effect.
Therefore, irritating animals are also useful in nature!
The Gjende blackfly (Metacnephia tredecimata)
The Gjende blackfly is a midge that is especially numerous at Gjendeosen. They hatch in August and September, and sometimes visitors can experience that the stones and boats are covered in so many midges that they look almost black.
Fish migrate to Gjendeosen during the late summer/autumn, both in search of food and to spawn. The fish at Gjendeosen eat a lot of Gjende blackflies. Sometimes, huge numbers of fish gather at the mouth of the river, and this provides fantastic and intense fishing conditions.
In 2019, Gjende blackflies were totally absent at Gjendeosen, and the trout suddenly became thin and are now in a poorer condition than earlier. Researchers are astonished about what is happening and are trying to find answers to these findings.
Red-thighed St Mark’s fly
The red-thighed St Mark’s fly is also an important insect in high mountain ecosystems. It is a species of March fly. The red-thighed St Mark’s fly is easy to recognize by its black body, the vein pattern in its wings and its red thighs. It flies rather slowly with its long legs hanging backwards. The red-thighed St Mark’s fly is widespread throughout the entire country. People easily recognize this insect due to its size and appearance, and it is also an important source of food for fish and birds. The red-thighed St Mark’s fly is also well-known in the world of sports fishing. When this large and rather heavy insect lands on the surface of the water, it can’t get back into the air again. This makes it easy prey for the fish. There is a fishing fly imitation of this insect.
Every now and again, we experience huge numbers of this large, fly-like insect everywhere, in the air, on the ground and on water surfaces. We’re talking about huge swarms. When red-thighed St Mark’s flies begin to swarm, it also means that insect-eating birds can enjoy this abundance of food before they start their autumn migration, like the golden plover. Some species also eat a lot of larvae and flies in years when there aren’t huge swarms. This is because the red-thighed St Mark’s fly is around during the late summer, when other insects aren’t present in these mountain areas.