Carrot fly
From Allotments4All
Common pests and how to deal with them
The maggot which this fly breeds attacks the roots of young carrots during the summer and ruins them completely. Keep the soil alongside the plants firm by trampling; use soot freely on the young plants. Moisten sawdust with paraffin oil and scatter it around the young plants. Carrot fly is a low flying creature and an alternative approach is to net the area around the carrot bed with a finely woven mesh to a height of 90cm.
