Cēsis bridge becomes insect marital bed for a night

Voldemārs Spuņģis, a senior researcher at the Faculty of Biology of the University of Latvia, explained to LETA that the bridge over the Gauja River is the site of a mating ritual, during which millions of water-dwelling insects simultaneously float in the air and cover the asphalt in a thick layer.

The entomologist explained that when the larva is fully grown, it emerges from the water, changes its skin and transforms into a subimago, or adult insect-like creature. The subimago then changes its skin again and finally becomes an adult insect - an imago. The mayfly, also called dayfly, gets its name because it lives only a few days, during which it does not eat but only mates. Mating usually takes place on warm, windless evenings, and by morning the females are laying eggs.

Spuņģis noted that mayflies tend to fly toward light sources, especially those with a lot of ultraviolet light in their spectrum, such as fluorescent light bulbs. The bridge over the Gauja is apparently illuminated with bulbs whose spectrum is attractive to the insect, and they have flocked to the bridge from all over the immediate area. The departure of adult mayflies is synchronous, occurring only a few days a year, when males and females are more likely to find each other.