Leaf Miners

by Richard Jones

Whilst out running in Peckham Rye Park earlier this week I noticed that the leaves of the horse chestnut trees are starting to show pale brown blotching all over.

Leaf MinersWhilst out running in Peckham Rye Park earlier this week I noticed that the leaves of the horse chestnut trees are starting to show pale brown blotching all over. These are caused by the caterpillars of a minute moth, Cameraria ohridella - the horse chestnut leaf miner. The tiny caterpillars, only a few millimetres long, chew away the inside of the leaf, feeding between upper and lower surface, and leaving the pale air-filled void. Each leaf can have up to 50 mines in it. The moth, a massive 7 mm from wing-tip to wing-tip is striped orange and white and quite pretty under a lens.

It had been spreading across Europe from its first discovery in Macedonia in the middle of the 20th century and arrived in the UK in Wimbledon in 2002. I first noticed it on the Rye in 2005 when trees on the south side were affected, but not the ones along the north.

The wet spring appeared to delay the mines, I noticed them in May last year but they have caught up with a vengeance. Even so, they do not appear to be as ravaged as those I saw in France last August. The Loire and Normandy countryside was dotted with brown trees amongst the green. These were horse chestnuts so mined as to have very little chlorophyll left in them. There were early fears that conker crops might be compromised by the combined herbivore stress of millions of tiny grubs munching away at the leaves, but we managed a good harvest from the park last September.

I also noticed the litter strewn around the park. Now, this isn't local yobs leaving their beer cans and fish and chip wrappers dumped on the ground, it's the leftovers of family picnickers. And it's not picnickers being lazy, because they have done their best to gather it all up and put their rubbish in the bins. Unfortunately, a local wildlife form has taken to undoing any dutiful garbage collecting. Foxes always used to get the blame for ripping open black plastic bags left out on bin day, but the critters making a mess all over Peckham Rye are grey squirrels which delight in sitting inside the bin chucking the contents out onto the ground as they scavenge for crisp wrappers and rotting egg and cress sandwiches.

Last Friday I was presented with a beautiful black, white and yellow moth found dead on the pavement outside Ivydale Primary School in Nunhead. It was a Jersey tiger moth, Euplagia quadripunctaria. It is common in the Channel Islands (hence its English name), and is now established in some places along the South Devon coast, but a couple of years ago it turned up in Lewisham, just one and a half kilometres away, and is now breeding in the area. The specimen is now in the proud ownership of Moon Class at the school.

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Gardeners' World Web User 28/11/2011 at 18:29

Hi I'm Living In Cologne Germany, I Do A little bit Of Guerrilla Gardening In My Vicinity. I Have 4 Horse Chestnut Trees On My Balcony Largest Being 2 Metres Tall Along with Several Oak Trees all Grown from Seed, There My Pride & Joy The Plan was To Plant Them In My Local Park, But They Seem to Be suffering From a Plague of Leaf Miner. Anyone Got Any tips on How To Control Them The chestnut Trees In The local Park Are Also under Siege but I'm more concerned About My Babies. Would really appreciate Any Advice. Slainte. Redbeard