Over the past couple of years, Butterfly Conservation has published two major reports on the state of butterflies and moths. These have found that overall moth abundance has fallen by over 30% in the past four decades, and that 80% of butterfly species have declined in that same period.
Like any gardener, I am nosy about what other gardeners are doing in their patch. So it happened that after the latest State of the UK's Butterflies report came out and the alarming statistics were rattling around my brain, I was walking along a street and looking at the front gardens. From the 20 houses I passed, I counted only two native trees in the whole street. Any hedges were of beech or privet. On another street in another part of town, the results were much the same. No native trees, no long grass, no wildflowers. As a consequence of all of this, there would be almost no caterpillars.
Butterflies and moths have evolved to lay their eggs upon certain plants only, and the great majority of these will be native plants. In the Field Guide to Caterpillars of Great Britain and Ireland by Barry Henwood and Phil Sterling, the authors give us a real insight into the lives of caterpillars. Caterpillars do their best to avoid being eaten by predators like birds. Just two of the many strategies are to look like parts of the plants they feed on or to become poisonous or unpalatable. This is why native plant species are important. Caterpillars of the Early Thorn are a good example - they are brown with various lumps and bumps that allow them to perfectly resemble the twigs of native trees like Hawthorn, birth and hazel that they feed on.
For the species that are unpalatable to predators, they have often evolved to be able to eat poisonous plants without being killed themselves, while using the harmful chemicals from the plants to make themselves less likely to be eaten. A familiar example of this is the Six-Spot Burnet, whose caterpillars eat the wildflower Bird's-foot Trefoil which is a source of cyanide. The caterpillars have bright yellow and black markings, and the adults are black with red spots - both clear warning signs to would-be predators that they would make a dangerous snack!
These are just two examples of the close relationship between moths and their foodplants, but this type of connection is present across the butterfly and moth world. Appreciating this is the key to helping butterflies and moths in our gardens. This is why Butterfly Conservation has set a goal to create 100,000 Wild Spaces across the UK. Wild Spaces are places where butterflies and moths can feed, breed and shelter. Using more native trees and wildflowers in our gardens will help with the 'breed' element of Wild Spaces.
You can look back through previous blogs to find out our recommendations from trees and shrubs and wildflowers. Even better, you can pledge to create a new Wild Space in your garden or community, and be kept up to date with more information and articles.