The small, beautiful Holly Blue butterfly, the only blue we get in our garden and the one you are most likely to see in parks and gardens in England and Wales, flitting low and fast, is back feeding on our flowers. Numbers of Holly Blue fluctuate greatly, thought to be due to the variable numbers of the parasitic wasp which lays its eggs in their caterpillars. The caterpillars feed on holly as the name suggests, but also on dogwood, spindle, snowberry and other common bushes. The female has a dark edge to the wing. Conditions: cloudy after heavy rain. Temperature: Max 19- Min 13 C.