Seven insect heroes of pollination

Pollinators spread the love

Flowers abound in spring and summer. Their generous offerings of colour, smell and nectar are all on show for one reason - to seduce a pollinator to pay them a visit. 

Pollinators carry pollen with them as they move from flower to flower. Their pollination services are essential for plants, including the ones we like to eat.  

Although honeybees get most of the credit, at least 1,500 insect species pollinate plants in the UK. In some parts of the world, birds, bats and even lizards also get involved. 

What is pollination?

Pollination is how flowering plants reproduce. Pollen needs to travel from the flower's male part, called the anther, to the flower's female part, called the stigma. Pollen is full of genetic information needed to fertilise a plant. Once fertilised, plants can make their seeds.

For some plants, the process of pollination is the work of the wind and rain. In other cases, flowers just pollinate themselves. But many species have evolved to get insects and other animals to do the work for them.

The relationship between plants and their pollinators is an ancient one. Researchers have found a tumbling flower beetle trapped in amber from the Cretaceous Period almost 99 million years ago. 

Plants provide sweet nectar and pollen for pollinators. In return, pollinators move pollen from one flower to another, fertilising the plant so it can produce seeds.

When interacting species live alongside each other for long periods of time, they can influence each other's evolution - this is called coevolution. Flowers and their pollinators are an example of this kind of close relationship. Over time, flowers have evolved shapes, colours and scents that maximise their pollination chances. 

Pollinators have also adapted to be able to access nectar from particular flowers. One example of this is the hawkmoth whose long tongue feeds from long flowers.

Why is pollination important?

Flowers need to be fertilised so they can make the seeds, fruit and nuts needed to grow seedlings and spread to new areas. 

Cross-pollinating with another plant of the same species allows for greater diversity in any new plants. This genetic diversity helps plants develop resistance to diseases and pests, and to evolve to changing conditions. 

Pollination is important for the food we eat. Crops such as apples need the help of pollinators to make fruit. In UK orchards, apple trees are pollinated by many different insect species. One study found more than 25 different bee and hoverfly species on apple blossom and showed that insect pollination tripled the production of fruit and boosted its size and quality. 

What insects pollinate?

The list of insect pollinators is long and includes many different species of bees, flies, wasps, beetles, butterflies and moths. Even species with a bad reputation such as houseflies and mosquitoes are important pollinators. 

For an animal to be an effective pollinator it needs to actively visit flowers of the same species and be capable of carrying pollen on its body (often unintentionally) so that it transfers from one flower to another. 

Meet seven underappreciated insect pollinators

1. Bumblebees

Bumblebees can vibrate their bodies to dislodge pollen from a flower. The bee then combs the pollen off its hairy body into little baskets on its legs, called corbiculae. This way of gathering pollen is called buzz pollination.

Most of the pollen collected will be taken back to the nest to feed young bumblebee larvae, but some grains will transfer to the next flowers the bumblebee visits.

Bumblebees can forage several kilometres from their nest, but this varies depending on the species. 

Some bumblebee species can also get up to cracking speeds of 15 kilometres per hour. 

Dr Joseph Monks, a bee expert and Curator of Hymenoptera at the Museum, says, 'While bumblebees forage from many plant species, an individual bumblebee during a single collecting trip may show floral constancy. This means the bee focuses on one species of flower during a foraging bout and thus acts as an important pollinator.' 

2. Hoverflies

Hoverflies are prolific pollinators. They are known to visit at least 72% of global food crops and over 70% of animal-pollinated wildflowers. 

Highly migratory, hoverflies can travel hundreds of kilometres a day. They can also carry pollen over distances greater than 100 kilometres over open water. Based on radar studies of two common European species, Episyrphus balteatus and Eupeodes corollae, up to four billion individuals fly into and out of southern Britain each year, transporting huge amounts of pollen in the process.

Some plants use deception to attract pollinators. The orchid Cypripedium subtropicum (which is native to southeast Asia) mimics aphids to lure hoverflies. The orchid's flower has hairy white tufts that look like an aphid colony covered with honey dew. It also emits an aphid-imitating smell. This leads certain hoverfly species whose young feed on aphids to wrongly believe the plant will offer their predatory brood plenty to eat. When the female lays her eggs, she picks up some pollen. 

3. Solitary bees

Solitary bees don't travel very far, although foraging distances vary among species. Most forage up to 500 metres from their nest and some as little as 100 metres. 

Like honeybees and bumblebees, solitary bees gather pollen to feed to their offspring, but they don't collect it in pollen baskets. Instead, the grains stick to a pollen brush, or scopa, which can be on the legs or under the abdomen, depending on the species.

Some solitary bees have an interesting relationship with a particular plant. The yellow loosestrife bee (Macropis europaea) forages exclusively from yellow loosestrife (Lysimachia vulgaris). Joe explains, 'M. europaea collects both pollen and oil from the plant. It uses the pollen to feed its larvae and the oil provides a waterproof lining to the nest cells, allowing the bee to nest in wetland habitats.'

4. Wasps

Wasps are hungry minibeasts with high energy needs, so many of them search for flower nectar. Wasps are not as hairy as bees, so pollen does not stick to them as easily, but they are still important pollinators.

Some wasps (in the family Agaonidae) have a special relationship with wild fig plants. In an alliance that is around 60 million years old, the fig plant needs to be pollinated by fig wasps. In turn, these wasps have evolved to live inside the figs and feed exclusively on them.  

5. Moths

Most moths fly at night, so you might not notice as they flit from flower to flower under the cover of darkness. Some nocturnal moths prefer to feed from pale and tubular, scented flowers, such as honeysuckle.

Pollen can get stuck to a moth's furry body and on its long tongue or face as it reaches down into the flower looking for nectar. 

Some species of moth can travel long distances, carrying the genetic information in pollen far and wide.

6. Butterflies 

Dr David Lees, Curator of Microlepidoptera (micromoths) at the Museum says, 'There are just 57 resident butterfly species in the UK, compared to more than 2,500 moth species.

'Due to this low species diversity, butterflies are not as important for pollination as some other insects, but their abundance in florally diverse meadows and chalk downlands, for example, can sometimes make them more important than moths for pollinating flowers during the day.'

Most UK butterflies are generalist pollinators, so they don't have a specific relationship with one plant. Butterflies can still help with cross-pollination of a single species though. For example, if you watch a hedgerow, you might see a brimstone (Gonepteryx rhamni) moving from flower to flower of the same species, such as bush vetch (Vicia sepium).

7. Beetles

'Beetles have been pollinating flowers for millions of years,' says Beulah Garner, the Museum's Senior Curator of Coleoptera (beetles). 'Over this time, evolution has perfected the insect-plant relationship and both insects and plants have evolved a great diversity of form and function.' 

Many different species of beetles eat pollen. For some, such as the aptly named pollen beetles, pollen is their main diet. For others, it is an additional tasty snack, including for some ladybirds that supplement their usual carnivorous diet of aphids with pollen. 

Beetle-pollinated flowers tend to make extra pollen so there is some left over to be carried to another flower on the beetle's body. 

The flowers tend to be smelly or fragrant, because beetles navigate by a strong sense of smell. Beetles are attracted to flat, open flowers, which allow them to graze, and flowers in clusters, such as cow parsley. 

Approximately a quarter of the UK's beetles are pollinators - so around 1,000 species. These include flower beetles, longhorn beetles, pollen beetles, soldier beetles, sap beetles, checkered beetles and scarabs. Some beetles are just incidental pollinators, moving pollen as they go about their daily business. 

Pollinators are under pressure 

Insect pollinator species are in decline as biodiversity loss around the planet accelerates. Human activities causing their decline include climate change, and habitat destruction and degradation due to urbanisation and agriculture. Light pollution is an additional threat to night-time pollinators. 

An estimated 84% of EU crops and the vast majority of wildflowers depend on insect pollination.

It is important that we make the world a friendlier place for pollinators so they can do their vital work.

Three things you can do to help insect pollinators

1. Grow pollinator-friendly plants in your garden or on your windowsill

It's easy to grow wildflowers in a planter pot and pollinators will love them.

2. Let your lawn grow a little wilder

Not only will providing additional areas where wildflowers can grow help to feed your local pollinators, but the caterpillars of many butterflies and moths rely on native grasses and plants generally considered weeds. 

The Museum is making a meadow on Museum Lane as part of our Urban Nature Project. This area will abound in wildflowers and be part of a bee superhighway in the London borough of Kensington and Chelsea. Connecting areas of wildflowers allows pollinators to move easily from place to place and gives them a larger habitat, or home. 

3. Build a home for solitary bees

Find out how to build your own bee hotel that can house solitary bees from year-to-year, as well as other ways to ensure these important pollinators have somewhere to nest.