Insects are present in Iceland, though their diversity is remarkably low compared to mainland ecosystems. The island nation, situated in the North Atlantic, is home to approximately 1,300 species of insects, a stark contrast to the millions found globally. This limited fauna is a direct consequence of Iceland’s geological history, extreme climate, and biological pressures that have prevented widespread colonization and speciation. Only the most cold-hardy and adaptable species have been able to establish permanent populations.
Environmental Factors Limiting Insect Life
The primary constraints on insect diversity in Iceland are geographical isolation and its highly variable, subarctic climate. The island has been separated by vast stretches of cold ocean, making it difficult for species to disperse from mainland Europe or North America. This isolation means only insects capable of long-distance transport, such as those carried by wind, ocean currents, or human activity, have been able to colonize the land.
The island’s northerly latitude and harsh weather feature short, cool summers and long, unpredictable winters. Cold temperatures directly impact insects, which require specific ambient temperatures for feeding, movement, and reproduction. While localized geothermal activity creates microclimates that support some insect life, the overall climate limits the food sources and habitats required by a larger, more diverse insect population.
The Common Terrestrial Insect Populations
Several groups of insects have successfully adapted to life in Iceland, with the order Diptera (flies and midges) forming the most diverse group. Chironomidae, or non-biting lake midges, are abundant in Icelandic freshwaters, where their larvae are a significant food source in aquatic food webs. Biting midges and black flies (Simuliidae) are also common near standing water and rivers, often becoming a nuisance during the summer months.
Other prevalent terrestrial insects include Coleoptera (beetles) and Lepidoptera (moths and butterflies). Common beetles, such as ground beetles and rove beetles, demonstrate adaptations for surviving the cold climate. All fully indigenous Lepidoptera representatives are moths, as true butterflies have not established permanent populations. These species employ life cycles that utilize the brief summer period for development or allow them to successfully overwinter as eggs or larvae.
Why Iceland Has No Mosquitoes
Iceland is known for its absence of mosquitoes (Culicidae), despite nearby regions like Greenland and Scandinavia hosting several species. The scientific explanation centers on the unstable nature of Iceland’s winter climate and its unique freeze-thaw cycles. In colder regions, mosquito larvae or pupae typically enter a dormant state (diapause) and hibernate beneath continuous ice until spring.
Icelandic winters, however, feature frequent, rapid temperature fluctuations. This causes water bodies to repeatedly freeze and thaw. This erratic cycle disrupts the mosquito life cycle, as pupae are repeatedly jolted out of diapause by a temporary thaw, only to be killed when the water refreezes. This disturbance prevents the larvae from completing development. Recent observations suggest this status may be changing, as three specimens of the cold-tolerant species Culiseta annulata were recently discovered, an event attributed to the island’s rapidly warming climate.