Cherry slug worms

When I noticed, a few days ago, that some leaves on a young cherry were being grazed, I didn’t give it much thought. It’s the time of year when caterpillars are everywhere and leaves are naturally heading into decline.

A cherry slug worm grazing on a cherry leaf
A cherry slug worm grazing on a cherry leaf

But, later on, a slimey black splodge on one of the cherry leaves made me look a little closer. And there was my first cherry slug worm. I’d learnt about cherry slug worms being a pest almost all over the world, but I had never seen one in the flesh, so to speak.

Cherry slug worms are the larvae of a sawfly – Caliroa cerasi. They coat themselves in shiney bluish-black gloop to put birds off from eating them. This gloop works so well that the slug-worms confidently feed in broad daylight on the upper surfaces of leaves. There they eat away all the flesh, just leaving a skeleton of leaf veins.

From this angle you can almost see through the black gloop to the greeny-brown larva within
From this angle you can almost see through the black gloop to the greeny-brown larva within

Cherry slug worms are also supposed to be quite happy eating hawthorn leaves, so after these two had had their photos taken, I moved them to a hawthorn bush. If they’re unlucky, they’ll be parasitised by a wasp; if I’m unlucky, they’ll pupate in the litter under the bush and emerge as flies to lay eggs and make more slug-worms next year!

2908cherryslugwormsgrazing 002

Advertisements

2 thoughts on “Cherry slug worms”

  1. I’ve seen a similar looking larva on the hawthorns here. They don’t seem to do much harm and like you say it is the end of the season. There’s another sawfly here that feeds on young pines and they can eat enough to kill whole branches. I usually find them when it’s too late.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s