Leaf miner moths
Conker trees...
You might recognise horse chestnut
trees (Aesculus hippocastanum). They’re
large trees often
found in parks, which
produce conkers in
the autumn. These
might be fun to play
with, but conkers
are actually slightly
poisonous nuts (if you
eat them!)
Miner moths
Horse chestnut trees provide the perfect
home for the leaf miner moth (Cameraria
ohridella). The moth is 5mm long and
has brown front wings with silvery
stripes and dark grey back wings.
After 4 weeks the larvae develop
(pupate) into adult moths.
Over the course of one summer,
leaf miner moths can go through 5
generations of moths (laying eggs,
larvae hatching and moths pupating).
The pupae are also able to survive low
temperatures (−23 °C) over winter in
dead leaves on the ground. The adult
moths then hatch out in the spring to
infect new leaves.
Tree damage not death
Leaf miner moths may seriously harm
trees, but they don’t kill them. The
mines created by the larvae simply
reduce the amount of photosynthesis
the tree can do. This reduces the
amount of sugar produced, stunting tree
growth and reducing the yield of seeds
(conkers).
Infected leaves have brown blotches
on them, caused by the leaf miner
tunnels, which may cause leaves to
drop prematurely. Where there are
lots of larvae, the tunnels can spread
throughout the leaf.
Larvae and pupae
The female moth lays between 20 – 40
eggs on the surface of a leaf. After 2 –
3 weeks, small caterpillar larvae hatch
out. These tunnel into leaves, sipping on
sugary leaf sap.
History
Back in 1879, a Greek botanist first
collected a miner moth whilst collecting
for other species. However the first
identification of the miner moth wasn’t
until 1984 in Macedonia.
Spread
The moth has only
recently arrived in the
UK, with the first the
sightings in Wimbledon
in 2002. Since then it
has spread throughout
the country causing
nationwide problems.
Control
Getting rid of this pest would be
extremely difficult, as it would involve
using toxic chemicals that would harm
other animals. Luckily, nature has given
us a helping hand: parasitic wasps!
Parasitic wasps:Alien
vs. Predator
The parasitic wasps lay their eggs in the
larvae of the leaf miner moth and when
the wasp eggs hatch, the larval wasps
feed on the larval moth, eventually killing
it!
One wasp species (Pnigalio flavipes)
can wipe out 90% of leaf miner moths.
These wasps are small (2-3mm) and
dark in colour. They hunt for leaf
miner larvae and sting them (causing
paralysis). The female wasp then lays
its eggs in the larvae. When the wasp
egg hatches it eats the leaf miner larvae
from the inside out!
Questions
1. What effect do you think the miner
moth would have on conker growth?
2. How do you think the wasps locate
the moths?
3. Why is the miner moth bad for our
woodlands?
Images
1. Horse chestnut tree Image by Sannse, Wikipedia. Released
under GNU Free Documentation License.
2. Leaf miner moth Image from: Carlos Lopez-Vaamonde et
al. (2010). Lepidoptera. Chapter 11. BIORISK – Biodiversity
and Ecosystem Risk Assessment 4. DOI:10.3897/biorisk.4.50
3. Leaf miner moth larvae Image by Beantree, Wikipedia.
Released under GNU Free Documentation License.
4. Leaf minder moth pupa Image by Varel, Czech Wikipedia.
Released under GNU Free Documentation License.
5. Image of infested leaves by Fritz Geller-Grim, Wikipedia.
Licensed under Creative Commons Attribution-Share Alike
3.0 Unported.
6. Map of leaf miner moth spread Forestry Commission
‘Horse chestnut leaf miner - Cameraria ohridella’
7. Image of male Diadegma insulare parasitoid wasp, and
mature larvae of Plutella xylostella. Photograph by Andrei
Sourakov, Florida Museum of Natural History.
Created by...
Contact
For more information please contact: [email protected]
More resources available on the BSPP site: www.bspp.org.uk