Creepy Crawlies and Poorly Trees – Educating Kids

Trees are like us and they get poorly too. They don’t get coughs and colds like we do, but they can be infected with diseases and different creepy crawlies. As we’re sure you’re all looking out for ripe conkers, we’ve included things that affect conker (horse chestnut) trees in this first blog post.

Horse Chestnut Canker

A canker is a sore patch on a tree. These sores are caused by a disease found in England and Scotland and that is becoming more common. The tree can look like it is sore or bleeding on the trunk and on the branches. Big trees can die from this disease, but smaller ones are most likely to die. If you see sores or bleeding like in the picture, ask an adult to inform the Forestry Commission. Further images of cankers can be found here.

bleeding on trunk
Bleeding on trunk of horse chestnut

Horse Chestnut Leaf Miner

Moth form of horse chestnut miner
Horse chestnut leaf miner moth

These moths are named because their caterpillars like to ‘mine’ into the leaves of horse chestnut trees. The caterpillars then eat the leaves. These tree pests are found in England and Wales.

Caterpillar of horse chestnut leaf miner
Horse chestnut leaf miner caterpillar

They don’t damage the tree but they make brown lines on the leaves and the leaves then drop off early (at the end of Summer rather than in the Autumn). Most infected trees are being monitored regularly, so you don’t need to report these infections.

Infected leaves
Leaves infected by leaf miner caterpillars

Suggested science activity: Take two leaves from a tree you think is infected. Brush off any insects you can see on the leaves and put them in a sealed plastic bag, keeping some of the air in the bag. Keep them out of bright light and store them for two weeks. If the tree is infected the caterpillars and moths should come out of the leaves.

Do you see any adult moths? Do you see any tiny wasps (these can eat the caterpillars)? Do you notice anything different about the size of the conkers of infected trees compared to uninfected trees?

Oak Processionary Moths

Found in certain spots in England, including London. The hairy caterpillar of this moth hurts oak trees by eating their leaves. The caterpillars like to walk together in a line or group to form a silky nest.

caterpillars of oake processionary moth in a line
Caterpillars of oak processionary moth in a line
Nest formed by the moths
Silky nest formed by oak processionary moths

Beware, they can give you a rash and make you very poorly if you touch them or any of their hairs. They can also make your pets poorly. Keep away from any caterpillars or any nests you find and ask an adult to alert the Forestry Commission.

(Adapted from info from The Woodland Trust, Forestry Commission and the Conker Tree Citizen Science Project)