Oecos trap trials for Horse Chestnut leaft miner moth (Cameraria ohridella)

The Horse Chestnut leaf miner is continuing its advance across much of the United Kingdom.  This pest of Horse Chestnut trees now occurs in most European countries.  The pest can have 3-5 generations a year and its pupae are front tolerant, so even harsh winters have little effect on its development.

The damage it causes is mainly cosmetic but there is growing evidence that continued damage may have long lasting effects on the growth and reproduction of the tree.  Conker weights are significantly reduced in damaged Horse Chestnut trees.  Reduced stem growth has also been recorded by researchers.  The caterpillars or larvae feed inside the leaf and can often be seen in the mines.  Infected leaves spread across the whole tree.  This gives the impression that the tree is dying.  Leaves also fall early from Horse Chestnut trees with bad infestations.

Oecos have been testing a pheromone based trap for trapping the adult Horse Chestnut leaf miners.  Tests and observations of the Horse Chestnut Leaf miner moth trap have been carried out for the last three years.  The pest produces massive numbers of adults in one season from multiple generations in the summer months.  This provides a potential to catch high numbers of adult moths and hence reduce the egg laying and subsequent levels of new damage.  The adults are very small and need a particular type of trap to catch and hold them in great numbers.  The Oecos castellation trap combined with a specific pheromone for attracting the male adult moths has proved it can catch vast numbers when hung in infested trees.

The traps featured in the images on display are from the trial in 2011, which follow on from trials from 2009 and 2010.  The images clearly illustrate the ability of the traps to catch high numbers of Horse Chestnut leaf miner adults.  They also record the different generations developing throughout the season.

In tree from 27th May and recorded until the 11th July

Tree without trap

Tree with trap

In the tree from 11th July and recorded until 31st August

Horse Chestnut trees in the Oecos trials that have had traps placed in them over the last three years visibly show less damage and are less prone to early leaf fall.

The use of the Oecos Horse Chestnut leaf miner traps over subsequent seasons has been observed to significantly reduce damage to Horse Chestnut trees from Horse Chestnut leaf miner moths.  The use of the traps combined with other treatments could provide an integral part of a strategy to minimise the impact of this rapidly developing pest.  This could help save this popular tree before landscapers and gardeners decide against planting new ones for fear of the Horse Chestnut leaf miner pest.

In the tree from 4th April and recorded until 27th May