New caddisfly species discovered in Scotland

A new species of flying insect has been discovered for the first time ever in Scotland on RSPB Scotland’s Insh Marshes reserve in the Highlands.

Molanna angustata is a small pale brown type of caddisfly with long antennae that lives in lowland lakes, ditches, ponds and canals.

Molanna angustata © Graham Calow -

RSPB Scotland Trainee Ecologist, Genevieve Dalley discovered and identified two male individuals from a moth trap while visiting the reserve in Kingussie in search of freshwater invertebrates.


M. angustata is fairly widespread across lowland England, up to the Lake District and Yorkshire, and in Wales. However, it has never before been found in either Ireland or Scotland, until now.


This particular species has a rather complicated lifestyle. The larvae live in water, where they create a protective case to live in out of tiny sand and stone particles, sticking them together with silk to make a tube.


When they have transformed to a winged adult they chew their way out of the case and swim up to the surface where they eventually fly away. However, this does have to be done quickly or aquatic predators, like fish, will eat them.


Genevieve Dalley, Trainee Ecologist at RSPB Scotland, said: “It is fantastic to have discovered this new species, especially since it is the first ever record of its kind in Scotland. Insh is a beautiful rare habitat which has avoided much of the damage and disturbance other wetlands have succumbed to, meaning insects like this caddisfly can live out their complicated lifecycle without disturbance.


“However, there is still a lot of work to be done if we want to fully understand this interesting little creature. We don’t know why it’s never been found in Scotland before – it could be that the species is starting to move north or it could be that this type of caddisfly has simply gone unnoticed until now. There is a Scottish alter ego to M.angustata called Molanna albicans, so it is possible that some angustata have been mistaken for albicans as they look the same. It is important to know the distributions of insects like this as they can be good indicators of large scale changes in climate or habitat. It would be good now to check other sites with similar habitat to Insh to possibly fill in any gaps, although that does have a slight air of looking for a tiny brown needle in a huge haystack!”