Dear Readers, as a member of the RHS I can get free gardening advice, and so I sent off photos of my lacy whitebeam leaves. Within 48 hours I had an answer, to species level (which surprised me) – my leaves are being nibbled by a sawfly, Cladius brullei to be exact. Also known as the Blackberry Sawfly, this little creature also loves the leaves of raspberries and hawthorn. In an average year there can be two generations, but during a hot year like this year there can be more. No wonder my tree looks a little sorry for itself.

What the hell is a sawfly, though? Well, first things first, it isn’t a fly, but a member of the Hymenoptera, which includes wasps, bees and ants. Sawfly females have ‘saws’ on their abdomen, which they use to cut open plant tissues when laying eggs. As most of these insects are fairly small, most species are very under-recorded, hence my delight at getting an identification right to species level. But what does Cladius brullei look like?

Here’s an adult male (Photo credit Andrew Green, taken from https://www.sawflies.org.uk/cladius-brullei/)

Lepidopterans and sawflies have caterpillars, but sawfly caterpillars have at least five pairs of ‘abdominal prolegs’ (those squishy ‘feet’ on the middle of the body) whereas butterfly and moth caterpillars have only four. Plus, lepidopteran caterpillars often have multiple sets of eyes (if you look closely at their heads), whilst sawfly caterpillars have only two.

Young caterpillar (Photo credit Rob Edmunds from https://www.sawflies.org.uk/cladius-brullei/)

Late instar caterpillar (Photo credit Rob Edmunds taken from https://www.sawflies.org.uk/cladius-brullei/)

Cladius brullei larva – Credit John Grearson. Count the legs!

The RHS have assured me that the damage to the leaves won’t cause any lasting problems for the tree – after all, it was already stressed after last year’s drastic pruning, so a bit of ‘pest’ damage is only to be expected. I certainly wouldn’t consider spraying or anything else – there have been lots of insects around this year (relatively), and I’m sure the blue and great tits will be enjoying the caterpillars. A slightly moth-eaten (or in this case sawfly-eaten) garden is, to me, a sign that it’s alive.