Curled Bracken fronds
The curled fronds on Bracken (Pteridium aquilinum) are caused by the tunneling larvae of the fly Chirosia grossicauda.
Blackish swellings on Bracken fronds
These dark swellings on the frons on Bracken are caused by the gall midge Dasineura pteridis. The leaf edges become rolled and thickened and eventually turn blackish in colour. Each roll contains a midge larva.
Bunched frons on Fern species
These distorted frons and stems are caused by the fly Chirosia betuleti. Once the larva has hatched it tunnels into the main stem and causes it to twist. This in turn causes some of the frons to become bunched and distorted.
All photos – Ashley Watson.