Garden insects

A predator of aphids and scale insects. According to Hodek & Honěk (Ecology of Coccinellidae, 1996), an adult consumes 20 to 60 aphids a day; the larvae, more voracious, can consume several hundred over their cycle. The popular figure of “200 aphids a day” is a generalisation.

The adult is soft green with large iridescent wings (“the golden-eyed maiden”), nocturnal, feeding on pollen and nectar. The LARVA = a formidable predator of aphids, and also of mites and whiteflies (McEwen, New & Whittington, 2001). Overwinters as an adult in shelters (barns, under bark).

A nocturnal generalist predator: slugs, snails, chafer grubs, eggs and caterpillars fallen to the ground. Predation of Colorado-beetle larvae stays marginal in Europe (documented mostly for Lebia grandis in North America). Garden species include the golden ground beetle (Carabus auratus) and the leather beetle (C. coriaceus).

Omnivore: a useful beneficial against aphids, but it can also nibble the petals and young leaves of dahlias, clematis and chrysanthemums when populations are high. To be regarded as a “beneficial to watch”. Precious in orchards, where it eats aphids (RHS).

One of the largest insect families, important in biological control (Quicke, 2014). Parasitoids: the female lays her eggs in or on a caterpillar, larva or pupa of a pest; the ichneumon larva devours its host from the inside. They mostly parasitise the larvae and pupae of insects, especially of moths and butterflies.

A tiny parasitoid micro-hymenopteran of the eggs of pest lepidoptera: European corn borer (Ostrinia nubilalis), cabbage white (Pieris brassicae), codling moth (Cydia pomonella). The female lays her egg inside the host egg, which blackens and then yields an adult trichogramma instead of a caterpillar.

A small bug, a generalist predator: mites, thrips, aphids, young caterpillars, pest eggs. Also pollen-feeding as a complement. Used commercially in greenhouse biological control (Orius laevigatus, O. majusculus), notably against thrips (van Lenteren, 2012).

A very large family of beetles, recognisable by their very short elytra that cover only the first abdominal segments. Generalist predators: fly larvae, pupae, eggs and larvae of other insects, small mites. The “devil's coach-horse” (Ocypus olens), a large black beetle nearly 3 cm long, lives in compost heaps and under stones.

The invisible worker of the soil: it aerates, drains, mixes the organic matter and produces casts very rich in nutrients. The meta-analysis by van Groenigen et al. (Scientific Reports, 2014) reports an average +25% yield in trials comparing soils with and without worms (pot and field trials, with residue inputs).

Formidable predators: adults hunt midges, mosquitoes and other flying insects on the wing, up to butterflies; the aquatic larvae eat almost any prey smaller than themselves (British Dragonfly Society).