Horse Chestnut Leaf Miner Trap
Horse Chestnut Leaf Miner (Cameraria ohridella) damage on Horse Chestnut trees is becoming a common problem in Southern England and is spreading into other areas. The adult moths lay hundreds of eggs, which develop into caterpillars that drill into the Horse Chestnut tree leaves. This causes the leaves to dry up and turn brown. This gives the tree a very sickly appearance and leads to early leaf fall, reduced seed vigour and poor germination. The damage is not fatal to the tree but one effect is the reduction in the size of the conkers from infested trees.
New Horse Chestnut Leaf Miner trap Oecos have developed a Horse Chestnut Leaf Miner adult trap. The trap contains a pheromone lure that attracts male Horse Chestnut Leaf Miner adults in huge numbers into the trap. Here they are caught and perish. This reduces mating leading to reduced egg laying. The traps do not totally stop damage or completely control Horse Chestnut Leaf Miner, but continued use of the trap over several seasons reduces the damage caused and can help to delay the early leaf fall caused by this pest.
Horse Chestnut Leaf Miner
damage close up
Horse Chestnut leaf miner & trap
Life cycle The adults are up to 5mm in length and are a metallic chestnut brown with white stripes edged in a black stripe. They appear from April, most from overwintered pupae in leaf litter. There can be 3-5 generations per year depending on the weather. Eggs are laid on leaves from May to August in large numbers. These eggs hatch in 2-3 weeks. The Horse Chestnut larvae develop in about 4 weeks inside the leaf tissue.
Trees using traps, at the end of
the season
Trees not using traps, at
at the end of the season
How to use Horse Chestnut Leaf Miner adult traps Before placing the trap in the Horse Chestnut tree; add the Cameraria ohridella pheromone lure into the top of the castellation trap. A small amount of water with detergent can also be added to the trap to ensure adults to not escape. Hang one trap per tree by April. Each pheromone lure will last about 6 weeks. After 6 weeks remove the trap and empty its contents. Add a fresh lure and put back into the tree. This should be repeated at least 3 times from April to the end of August. This will ensure that new generations of Horse Chestnut leaf miners are caught. In the Autumn the traps can be removed, cleaned and stored for use the following season. New pheromone lures can be purchased to re-activate the traps the following spring. It is recommended that the traps are used each year to reduce numbers and damage.
Leaf litter should be removed after leaf fall and burnt. This will significantly reduce the amount of overwintering Horse Chestnut leaf miner pupae.
