The larva of the gall-midge Dasineura urticae causes galls to form on the leaves of Common (Stinging) Nettle and Annual Nettle. The galls are pouch swellings of midrib, leaf, petiole or flower stalk.  Occasionally they are found in flowers or stem.  There is an opening on the upperside. 

The larva is white, but according to Redfern and Shirley (2011) there may be pink, orange or red inquiline larvae inside. . 

Dasineura dioicae also causes galls on nettle, a thickened leaf margin loosely rolled upwards and reddened. 

Gall  Adult

Anywhere that the host plants grow

The eggs are laid in the base of the leaf or in the main leaf veins. The larvae then cause a 'pouch' to form in the leaf structure and from this enclosed retreat they consume the inner tissues of the leaf.

Common and widespread in Britain

Common in Leicestershire and Rutland