Several species of butterfly feed on the grasses and flowers, including the ringlet, gatekeeper and the Essex and small skipper. Day flying moths can be found here too, including the six spot burnet. This striking red and black moth is extremely poisonous, containing cyanide derivatives to deter birds.

The quarry and wetland

In the north-western part of the reserve the old quarry remains, providing a mosaic of habitats and a unique chance to see Swaddywell's important geological features. The quarry exposes an outcrop of the lower beds of Lincolnshire limestone. The limestone formed as a marine sediment in warm, sub-tropical waters some 160 million years ago when the area lay in latitudes about equal to present day North Africa. These sediments were lifted above sea level at various times, the latest being during the formation of the Alps some 60 million years ago. Perhaps the most interesting feature is on the north side of the quarry. The limestone beds dip steeply and lie over a white, sandy exposure. The exposure of these rocks is due to a fault the Tinwell-Marholm fault. Over the years the disused quarry has gradually flooded, creating a patchwork of open water, reed and scrub. It also contains small areas of grassland with banks of wild marjoram and other flowers.

One of Swaddywell's most important natural features is its population of great crested newts. Although internationally scarce, this amphibian is common around Peterborough. In spring and summer, the quarry is alive with 14 species of dragonfly. Perhaps the most obvious is the emperor dragonfly. The emperor is the largest British dragonfly and aggressively hunts over the ponds, clashing in aerial duels with rival males. It can fly up to 40 mph, hunting out flying insects, including smaller dragonflies. The reserve is also home to two tiny, but pretty moth species the beautiful chinamark and the ringed chinamark. In July both can be found in the reeds around the main pond. Unusually the larvae of these moths are aquatic.