Barley Barley Crop Icon Brassicas Brassicas Crop Icon Sugar Beet Sugar Beet Carrots Carrots Icon Leeks Leek Icon Maize Maize Icon Oilseed Oilseed Icon Onions Onions Icon Other Cereals Other Cereals Icon O R T Peas And Beans Peas and beans Icon Potatoes Potatoes Icon Salad Crops Salad Crops Icon Soft Fruits Crops Soft Fruits Icon Top Fruits Crops Top Fruits Icon Wheat Crops Wheat Icon Calendar Calendar icon Arrow Next Arrow Previous Close Checkmark

Leaf blotch miner

1. Leaf blotch miner damage.
2. Leaf blotch miner lava.
3. Close-up of leaf damage.

Identification

The larvae can be readily found in the leaf mines and are white, translucent, 4-5mm in length with an indistinct 'pointed' head end.

Symptoms

The feeding tunnels of leaf miners can easily be seen giving the affected area a 'silvery' appearance. Whole leaves can be affected. The larvae do not tunnel into the stalks, stems and growing points which limits the damage to individual plants. Numerous larvae (6 plus) can be found feeding in each 'mine' at the same time. The older plant leaves are more likely to be attacked than the younger developing leaves.

Life-cycle

Eggs are laid near the leaf veins from which the larvae emerge to mine into the leaves. When fully fed they exit the leaves to pupate in the soil before the onset of colder conditions in the early winter.

Importance

The leaf blotch miner is less common than the cabbage leaf miner (Phytomyza rufipes), however the leaf blotch miner was widespread on oilseed rape in the warm dry autumn of 2009. Damage from mining can lead to leaf loss but after pupation new leaves will grow away normally without any loss of individual plants or crop yield. Insecticidal seed insecticide treatments did not seem to be particularly effective in controlling this pest in autumn 2009 but this might have been due to the exceptionally dry conditions preventing movement of the chemical from the outside of the seed in to the roots and shoots of the developing plants.

Threshold

Although potentially giving cause of concern, especially if crops are struggling to establish in adverse conditions, the larvae do not move from the leaves into the stems and growing points. As oilseed rape plants can tolerate loss of older leaves, treatment with insecticides is not normally considered to be necessary.

Identify Pests

Find out more information and help identify the pests found on your crops.

View now