Gardening with insects

Whilst not always obvious to us when we are busy working in our gardens, insects and other small invertebrates play an important role pollinating our flowers and vegetables, as well as tidying up dead and waste material. So here are 10 simple steps to make space for insects in your green spaces.

Quantity, quality & variety

Aim to provide lots of varied forage for all types of insect such as butterflies, moths, beetles, flies and bees. A bee may visit 100 flowers up to 10 times a day collecting nectar (sugars), pollen (proteins) and resins (lipids) to meet its needs. Also adult insects such as a butterfly may feed on a different plant from its larvae or caterpillar so you need to provide both plants if that species is to complete its lifecycle.

Image: A worker Buff-tailed Bumblebee (Bombus terrestris) feeding on lavender.

Four seasons

Whilst March to September is the main season for insects some will forage at other times of the year if the ambient temperature reaches 10 degrees or more. So planting flowers that bloom in a sequence during spring, summer, autumn and winter is vital for insects. Flowers that produce nectar at night are important for moths and species that constantly 'refill' with nectar during the day such as borage are of particular value for bees.

Image: Herald Moth (Scoliopteryx libatrix) resting on a flower of a pyracantha bush.

Mow less & love weeds

Many lawn 'weeds' such as dandelion provide vital forage for insects especially the early emerging queen bumblebees and some of the smaller species of solitary bee. Mow less often and cut your lawn at a height of between 3.5cm to 5cm until late May to avoid harming low growing plants such as clover. Also consider leaving some areas of lawn uncut until autumn so that they grow long and wild for skipper butterflies, grasshoppers and crickets.

Image: Solitary bee feeding on an early-flowering daisy.

Off the spectrum

The photoreceptors of insect eyes see from yellow, blue and green light through to the ultraviolet scale so that insects find blue, violet and purple flowers particularly attractive. Under UV light white and yellow flowers have 'invisible' markings to attract insects to their supplies of nectar and pollen. Red flowers are not popular with most insects.

Image: A male Green-eyed Flower Bee (Anthophora bimaculata) with unusual opaque eyes.

Flower fidelity

Pollinators may be selective during foraging so that honey bees for example will target one species of flower during the day or on a foray. Planting large clumps or drifts of one species of flower or a large flowering shrub can help insects save energy during foraging trips. Some insects are very specific in their choice of food plant as either an adult or larva or both. For example the familiar Peacock (Inachis io) butterfly will collect nectar from any flower but will only lay its eggs on the leaves on common stinging nettle (Urtica dioica).

Image: Orange-tip Butterfly (Anthocharis cardamines) feeding on garlic mustard.

Native or not?

Insects have evolved alongside flowering plants and both are attuned to the region in which they are found naturally. So whilst adult insects may feed on nectar from any flower their larvae may need a specific food plant to complete the species life cycle. For example the Chalkhill Blue (Lysandra coridon) butterfly larvae will only feed on horseshoe vetch (Hippocrepis comosa) growing abundantly in chalk and limestone grassland. It is therefore important to provide native plants to support thriving insect populations.

Image: Hazel Saw-fly (Craesus septentrionalis) larvae feeding on hazel (Corylus avellana) leaves.

Trees & shrubs

Some insects, especially beetles, live, breed and feed in trees and shrubs so perennial shelter and forage provided by hedgerows and shrubberies is vital for these species. Native trees and shrubs tend to support a greater diversity of insects, as well as the birds and small mammals that feed on them. Flowering and fruit-bearing species are particularly valuable for wildlife and woody herbs such as lavender attract lots of pollinators. Dead wood and decay is important habitat for some beetles.

Image: Female Stag Beetle (Lucanus cervus) will lay its eggs in dead wood.

Keep it simple

Not all insects that feed on nectar have long tongues like the bumblebees, butterflies and moths so it is important to select a variety of simple and native flowering plants rather than showy ornamental types. This will help ensure that nectar, pollen and resin is readily available to a broad range of insects visiting your garden. Many carniverous insects that predate on 'pests' (herbivores) eating your vegetables will top up their energy reserves for flight by drinking nectar of flowers.

Image: Hoverfly (Episyrphus balteatus) feeding on native common knapweed.

Water, water everywhere!

Water is vital to all life on our planet but insects cannot store reserves in their bodies so will forage for it when needed. They will drink from the smallest of sources so whilst ponds are a vital habitat for aquatic species you can help most insects by having bird baths, upturned bin lids and saucers of water. If you create a wildlife pond it should not contain fish as they tend to eat all the aquatic insects and amphibian larvae. Aquatic wildlife loves ponds with lots of marginal and floating plants in which to hide rather than open water.

Image: A female Emperor Dragonfly (Anax imperator) laying her eggs in pond.

Organic gardening

The main threat to wildlife in gardens is us and our over-use of power tools, machinery and chemicals. There are many low impact organic methods for gardening that will benefit wildlife and people too. Avoid the use of all chemicals, buy peat-free compost and use hand tools to help protect wildlife. An organic garden will be alive with insect predators that will eat the 'pests' (herbivores) dining on your fruit and vegetables.

Image: The Greenbottle Fly (Lucilia caesar) is one of nature's cleaners dining on carrion and manure!