Finding Roots

London’s Insect Guide

Written by Isobel Watts | Monday 21st June 2021 | Reading Time: 4mins

There are a massive 27,000 different types of insects in the UK, all playing a vital role in our world: contributing to keeping our ecosystems healthy, maintaining the food chain, and caring for our plants. They live amongst us, in gardens, woodlands, farms, and cities. For every person alive, there are 200 million insects! And so many of them go unappreciated.

Here we’ll be celebrating the insects that we share London with, discovering more about their secret lives in the air, on the water, and on the ground.

Ladybirds – Seven Spot Ladybird (Coccinella septempunctata)

These carnivorous beetles are well loved for their whimsical appearance and their food habits alike. They’re a gardener’s best friend, munching their way through up to 5,000 aphids each! These green and black flies are pests that smother many plants found in gardens, parks, and allotments, from roses to runner beans, so this is where you’ll see ladybirds too.

The Seven Spot Ladybird, one of the most common of our 47 native ladybirds, can be seen from March to October, after hibernating in hollow plant stems and cavities for the winter. In the last few years, the Harlequin Ladybird has colonised much of the UK, after arriving from overseas in 2004. Their arrival saw a decline in native species, as the larger Harlequins not only out-compete them for food and habitat, but also eat their UK cousins!

The number of spots on a ladybird has nothing to do with their age, as some myths may have you believe, but depend on the species of ladybird it is. For example, the Seven Spot Ladybird, as the name suggests, has 7 black spots dotted on its red wing cases. The thousands of different species of Ladybird come in lots of different colours, with most having red, orange, or yellow backs with black spots, or black backs with red, orange, or yellow spots. These striking colours act as a way to warn predators that they are toxic, but some will still try their luck. Another defence mechanism that they use is releasing a pungent yellow substance (‘reflex blood’) from their joints to deter predators.

Solitary Bees – Red Mason Bee (Osmia Bicornis)

The solitary bee is an often-overlooked pollinator, as species like honey bees and bumblebees enjoy all the fame.

Many of the 200+ species of solitary bee in Britain make their homes in urban areas. The Red Mason Bee gets its name from its habit of nesting in the cavities of buildings such as cracks in mortar joints, window frames, and air bricks, although they also nest in natural cavities like bramble stems, dead wood, and holes in cliffs or soil faces. They also appreciate bee hotels put out by humans.

These solitary bees enjoy the pollen and nectar of spring flowering shrubs and trees like apples and pears. They will also feed on cultivated garden plants, as well as visiting agricultural orchards and oilseed rape fields.

Red Mason Bees are active and pollinating from March – June, and usually breed at the end of this period. After mating, the female chooses a sunny nesting spot close to a pollen source and starts building her nest. She creates ‘cells’ which she lines with mud and fills with pollen, then lays a single egg and seals the cell, leaving the young to fend for itself. She does this for each egg, which could be up to 40 per bee! The eggs hatch into larvae, pupate in autumn, and overwinter until they emerge in the Spring.

Red Mason Bees are renowned for their success and efficiency as pollinators. It is said that a single female Red Mason Bee can pollinate the same amount as 120 honey bees! There’s even talk of breeding them commercially to pollinate fruit orchards in the future.

Butterflies – Red Admiral (Vanessa atalanta)

Butterflies are probably one of the most popular insects, admired by many for their elegance and bright colours. The Red Admiral is one of our largest and most easily identified butterflies, as its combination of red, white and black colourings won’t be found on any other butterfly.

Butterflies are pollinators, drinking nectar through their tongues like a straw. Red Admirals particularly enjoy buddleias, flowering ivy, and rotting fruit, whilst their caterpillars feed on nettles. They can be seen in all sorts of habitats, from gardens to the seaside, and cities to mountain-tops!

Most of these butterflies are immigrants, flying over from North Africa and continental Europe in the spring and summer. The females lay eggs on arrival, which hatch from July onwards, bringing in the new generation of Red Admirals. Although they typically hibernate further south, in recent years there have been some of these butterflies overwintering in southern parts of the UK and emerging on particularly warm days in early spring. It is thought that they can do this because of the increasingly warm winters that we are having in the UK.

Moths – Lime Hawk-Moth (Mimas tiliae)

Moths, the hairy nocturnal relative of the butterfly, can get forgotten or discounted as ‘creepy’ by some, but they form an important part of the food chain and can be quite beautiful.

There are over 2500 species of moth in the UK, a common yet elusive London resident being the Lime Hawk-Moth. The adult’s variety of pink, grey, and green patches give it a camouflage look, which is helped by the scalloped edges of its wings.

Although it happens to be green, this moth was not named for its colour. Instead, the Lime Hawk-Moth was named after its caterpillar’s taste for the leaves of lime trees. They also feed on elms, alder, silver birch, and plane, though the adult moths don’t actually eat at all!

After the caterpillar has spent the winter as a pupa, the adults appear in May and June, and can be seen during the day resting on walls, tree trunks, and lime foliage to avoid catching the attention of predators. However, this clearly doesn’t always work, as Blue Tits are estimated to eat around 50 billion moth caterpillars each year in Britain and Ireland!

Dragonflies – Emperor Dragonfly (Anax Imperator)

If you’re lucky enough to live close to water, or visit lots of parks with ponds, you’ll know how fascinating it can be to watch the dragonflies flit about the water. The Emperor Dragonfly, one of the largest dragonfly species in Europe, is especially impressive. The males are a striking blue colour, with a black stripe running down and a green thorax, whereas the females are mainly green.

They are common in large, well vegetated ponds and lakes, but can also be found in canals, ditches, and slow moving rivers. The females lay their eggs alone on the surface of the water, often in floating pondweed. These dragonflies spend up to 7 years as underwater larvae, known as nymphs, before emerging as adult Emperor Dragonflies on warm, sunny days.

They are active from June to August and are common in urban areas where there are lots of smaller insects for them to eat, such as butterflies and chaser dragonflies. They search for prey by flying up high and swooping in to catch it in mid-air. They even eat their prey whilst still in flight!

Shield Bugs – Common Green Shield Bug (Palomena Prasina)

You’ve probably seen one of these bright green shield-shaped bugs outside, maybe even in your house, but may not have known what it was. Out of 30 different species of shield bug in Britain, the Common Green Shield Bug is one of only 2 species that are green; the rest are all brown or yellowish-green. The other is the Southern Green Shield Bug, which arrived from Europe in 2003, and differs from the native bug in that they do not have tiny black spots and their wings are pale instead of dark.

The native Common Green Shield Bug, though often mistaken for a beetle, is part of the ‘true bugs’ group, meaning that it has a sucking mouthpart. It uses this feature to suck sap from a wide variety of different plant species to feed, yet doesn’t cause any noticeable damage and is completely harmless to humans. The Southern Green Shield Bug, however, can cause damage to some vegetables such as runner and French bean pods. Fortunately, these bugs are more numerous in the late summer and early autumn, which is after the cropping period, meaning that they are not yet becoming a pest.

Common Green Shield Bugs can be seen from May – November, particularly in Southern England. They lay their eggs in spring in clusters on the underside of leaves, which develop into nymphs by June and into full adults by early autumn. You can often see the adult bugs in the late summer sitting on various plants basking in the sunshine!

Hoverfly – Marmalade Fly (Episyrphus Balteatus)

Hoverflies are a common visitor in all sorts of habitats, from farmland to cities, and unlike other pollinators, they can be seen all year round. Although easily distinguished from other flies by their clear yellow/ orange and black striped bodies, their appearance often gets them confused with wasps, and sometimes bees. Because of these visual similarities, people sometimes worry that a hoverfly might hurt them, but don’t worry, they don’t sting people and are only interested in your flowers! You can tell a hoverfly from a wasp because they do not have long antennae or a bulging abdomen with a wasp waist; their bodies are straight and narrow.

Hoverflies are a welcome guest in gardens, as the adults are effective pollinators and the larvae provide pest control by eating those pesky aphids. The most common of the UK’s 270+ species of hoverfly, the Marmalade Fly, enjoys feeding on the nectar and pollen of flowers such as tansy, ragwort, and cow parsley in gardens, hedgerows, parks, and woodlands. They appear in large numbers in the summer, and often gather in groups on their favourite plants.

The Marmalade Fly was named for its orange colour, as well as the varying thicknesses of its black stripes. There are thin and thick bands of black, just like there are thin cut and thick cut types of marmalade!