Harlequins and Brimstones

Richard Stewart observes a predator

Ever since Julian Dowding ’ s successful campaign to increase the planting of buckthorn in East Suffolk, we have waited patiently for Brimstone to visit the one in the far corner of our garden. A few male Brimstone butterflies have passed through but never a female.

However in 2008, just after Marie had pruned our buckthorn, a male Brimstone was seen in our front garden and a female around the buckthorn. The date was May 12th and both were seen again on the 13th, with just the female the next day. Peter Locke, who has offered to help with my Fynn Valley transect walk, mentioned recent Brimstone sightings along a hedge of mixed native species, including buckthorn, at the Millennium cemetery, scarcely a mile from our garden and no great distance for a female Brimstone searching for egg-laying plants.

On June 4th four small Brimstone caterpillars were found on the buckthorn, with a maximum count reaching nine on June 22nd. This corner of the garden is well used by foraging birds, including families of Long-tailed Tit, but the green Brimstone caterpillar is well camouflaged against the leaf’ s central spine, though more obvious if it rears up or moves as it feeds.

After that the numbers declined and just one much larger feeding caterpillar was there on June 30th. We had no more sightings but knew pupation occurred away from the buckthorn. To our delight a freshly emerged female Brimstone, almost certainly from our garden, was feeding on buddleia on July 26th.

There was, however, just one initial problem. When we found the first four caterpillars one was almost gone, being devoured by what we soon realized was the larva of the rapidly increasing Harlequin Ladybird. Despite our vigilance and quickly removing any we saw on or near the plant, a Harlequin larva managed to take another one the next day. No further predation was recorded. Much concern has been expressed about the adult Harlequin ’ s effect on our native ladybirds, but look out for the larva as well. They appear to be voracious, with a catholic diet that almost certainly includes caterpillars of most species they discover.

Brimstone by Beryl Johnson