Hainault Forest Website

Written and Designed by Brian Ecott

Aquatic Minibeasts

POND SKATER Gerris sp. 15mm long. Common bug on all the forest ponds. Feeds on dead insects on the water surface. Bristles on the tips of legs prevent it breaking through the surface film. Photo: July 1973 WATER SCORPION Nepa cinerea. A  leaf-like, flat bug 30mm long. Two front legs adapted for grasping prey from which it sucks juices. The "sting-like" appendage at the rear is in fact a breathing tube which it uses like a snorkel. Photo: May 1971.  Chigwell Row Pond. LDER FLY  Sialis sp. Lays eggs on plants overhanging water. The larvae hatch and fall into the water and are carnivorous.  when developed crawl out of the water and pupate in the mud. Adult flies hatch May-June.  Photo: 11th May 2006.

A MAYFLY LARVA. Ephemeroptera. The larvae have three long tail appendages, and external gills on the abdominal segments, which are varied and used in identification of species. 12mm long. Common in the forest ponds. Photo: July 2004. Sheepwater. A MAYFLY.  Ephemeroptera. Wings held upright. Long tail filaments 2 or 3 in number. Have a brief adult existence for mating and egg laying.  Photo: July 2000.


A small crustacean 10mm related to the woodlice. Common in all forest ponds. Withstands pollution and low oxygen levels. Photo: July 2004  Sheepwater.

BACKSWIMMER Notonecta glauca. 15mm long. Common in all forest ponds and numerous in Sheepwater.  Often seen resting near the surface of the water where they gather oxygen. Photo: July 2004. As its name suggests The Backswimmer or Greater water boatman swims upside down The third pair of legs, covered in hairs, are the longest and used to row through the water. Far right: Microscope view of tip of third leg showing hairs which help to propel it through the water.

Long bodied DRAGONFLY LARVA, Anisopterid or Hawker type.  Dragonflies occur in all the forest ponds. They are carnivorous.

Photo: July 2004. Sheepwater.


Libellulid type. Photo: May 1998

DAMSELFLY LARVA,  Zygoptera. Distinguished from all other aquatic larvae by the three leaf-like tracheal appendages or "gills". Predatory, often lurking among water plants awaiting prey. Photo: May 1998 Several species of Damselfly occur in the forest ponds. 


Dytiscus marginalis. Up to 50mm A voracious carnivore. The tail filaments are fringed with hair and adhere to the surface film to obtain oxygen. Photo: May 1998.

GREAT DIVING BEETLE LARVA hanging from the surface film. Note the two powerful mandibles which are used hold the prey to enable it to suck out juices from its prey and to dissolve the solid parts.  Photo: July 1971. GREAT DIVING BEETLE LARVA feeding on mayfly larva. Photo: May 1998.

WANDERING SNAIL Lymnaea peregra.

20mm length. Plentiful in Sheepwater. Like the other snails illustrated here they need to rise to the surface to obtain oxygen.

Photo: July 2004  Sheepwater.

GREAT POND SNAIL Lymnaea stagnalis. A large snail up to 55mm in length. Lays sausage-shaped gelatinous masses of eggs on stems and under leaves of water plants.  Common in Roe's well. Photo: July 2004  Feeds on algae which it rasps from the surface of plants and rocks. It will also eat animal matter.

RAMSHORN SNAIL Planorbis sp.

20mm across. Common in Roe's well.

Photo: July  2004



Wandering snail Lymnaea sp

Pond snail Physella sp.

Short, fat bodied, dragonfly nymphs of the Libellulid  type which include the Darters.

Newtpole, feathery gills and four limbs

Diving beetle Dytiscus sp.

During mid June Raymond Small and myself visited all the ponds and streams in the forest, with a net,  to see what we could find there.

Raymond photographed all of our finds  and some are included here. We hope to do more as the summer progresses.

At the end of June there had begun a migration of toadlets and froglets from the Lake.

One of the best areas was the small stream which starts at the second car park and originally drained the Farm pond adjacent.

Tadpoles in various stages of development  (above and top)

A newt tadpole with four legs and feathery gills (above)

Water fleas Daphnia pulex  were found in the Lake in astronomical numbers during June. Each dip of the net produced a large handful. These form the base of a dynamic food web.

Damselfly nymph. Spends a year in the water before becoming a damselfly

Horse leech Haemopsis sp. Not a blood sucker but feeds on small creatures and dead fish. Head is the narrow end.

Water Hog louse aka Water Slater Asellus sp. Abundant in stagnant ponds

Freshwater shrimp Gammarus sp. Abundant in stagnant ponds

Back swimmer or Water Boatman Notonecta glauca. Third pair of legs have fringes of hairs to aid swimming. Take air from the surface through their elytra or wing cases which they push up through the meniscus.

Blood worm larva of the Chironomid midge Chironomus sp. Lives in polluted water and contains a form of haemoglobin to help with oxygen transfer.

Rat-tailed maggot, larva of a hoverfly Eristalis sp. Lives in murky water.Its extendable "tail" is a breathing tube, used to reach to the water surface to take in air.