How to control Leaf Minor
Leaf Minors are exactly what the name suggests, they mine the leaves! They start as a small 1-2mm long orange/browny larvae/maggot. They feed off the insides of in-between your leaves leaving small visible tunnels and excrement within the tunnel which increases in size as they grow. After about 3 weeks they change into adults, who then lay eggs within the leaf after a week they will hatch into larvae and the whole process starts again.
Leaf Minor tend to enjoy the leaves of beetroot, spinach, tomatoes, peppers, alliums and chard's. The adults start to suck the sap out of the leaves, leaving small cream/white puncture holes, which the females lay eggs in. Once the eggs have hatched they will burrow through your leaves and leave lots of tiny tunnels which can be seen with the naked eye. Leaf minor damage doesn't have much impact in the growing of the plant but if left your veggies growth can be slowed down and you chard's and spinach will look awful.
At the start of the growing season keep on top of your weeding, this is where leaf minors usually start. Regularly check your plants for the first sign of the adults which are usually quite hard to spot, but you can see the white/cream spots left on the leaves. Hang sticky traps around your garden to help stop them in their tracks. As soon as you see the tiny tunnels forming, remove and destroy them. Do not put the infested leaves on your compost heap or leave anywhere near your plants, dispose of them fully by burning or dispose in your green waste bin away from your garden or drown them for a few weeks and then place in your compost heap.. This way they will not carry on the cycle on any other plant of yours. If you do see the larvae/maggots squish them in your fingers and then dispose of them. Attract birds to your garden to help eat the adult flies and you could cover your vegetables with an insect proof mesh. In the autumn/winter when you are preparing your ground for the following spring dig in as deep as you can to bury any pests that are over wintering within the soil.
Tips on controlling leaf minors
Try planting radish near to spinach, the leaf minors will bury through the radish leaves which will have little effect on the growth of the Radish underneath.