Leaf miners

Introduction

There are four leaf miner species which are common pests: the tomato leaf miner (Liriomyza bryoniae), the American serpentine leaf miner (Liriomyza trifolii), the pea leaf miner (Liriomyza huidobrensis) and Liriomyza strigata. Under natural conditions, the larvae of these species are well parasitized by several natural enemies. Problems with leaf miner have increased as a result of the use of broad-spectrum pesticides: natural enemies are killed and the leaf miners develop resistance to these insecticides.

 

Biology

The leaf miner goes through six stages, namely egg, three larval stages, pupa and adult. The adult leaf miners are small, yellow and black coloured flies. The larvae form mines in the leaves of plants. Pupation takes place mostly in the soil.

 

Damage symptoms

• Larvae cause mines. This can lead to cosmetic damage, leaves drying out or even early defoliation. The latter may affect the yield.
• Female adults cause feeding marks where they feed. This gives cosmetic damage to the plants. Indirect damage occurs when fungi or bacteria enter the feeding areas.