Pollinators: Flies

This is a continuation of our series on pollinators. In this article I will cover flies, often overlooked pollinators of many plants.

As usual, keep in mind that a lot of the plant examples are not exclusively pollinated by a single pollinator. Often there can be several different pollinators visiting the same type of flower. For example anything that a fly can pollinate is usually also visited by bees.

Large Flies

I’m generalising larger flies into a single guild, and it is likely this group can be divided up into several sub-groups, but fly pollination is so poorly studied that we do not have a very broad picture of what flies are doing on flowers.

Flies usually feed on nectar when they land on flowers. Since they aren’t as fuzzy as bees, they don’t pick up as much pollen, but some are hairy enough to transfer pollen. Mango farmers take advantage of flies by putting prawn shells around their farms. This attracts carrion flies which then also pollinate the mango flowers.

Hoverflies are sometimes mistaken for bees. An easy way to tell hoverflies from bees is their flight pattern – they fly less frantically than a bee. They are not as fuzzy as bees and usually spend more time on flowers. They also tend to have shorter antenna compared to bees.

While pollinating they hunt for smaller insects and are good natural pest control.

Examples: Hoverflies (Syrphidae), Carrion flies (Calliphoridae), Flower flies (Anthomyiidae)

Flower structure: Fly-pollinated flowers tend to be shallow and grow in clusters.

Plants that they pollinate: mangoes

Small flies and midges

Small flies are very important pollinators of important crops, without them we wouldn’t have cempedak, nangka or chocolate.

Some are very small and can hardly be seen while flying. These flies typically are attracted to downward facing flowers that are close to the ground. Some plants like Aristolochia have elaborate trap flowers that trap the flies for a while until they pick up enough pollen.

Examples: Small fruit flies (Drosophila spp.), Scuttleflies (Phoridae), Midges (Nematocera)

Flower structure: Usually not brightly-coloured, tube shaped flowers

Plants they pollinate: nangka, cempedak, cocoa, Aristolochia

Carrion feeders

This group of insects feed on carrion and other rotting material. Some plants take advantage of this by pretending to be rotting meat with foul-smelling and dark reddish or purple flowers.

While the confused insects, (usually carrion flies or carrion-feeding scarab beetles) crawl around the flower in search of food, sticky pollen gets all over them. When they give up and leave the flower, they bring the pollen to other flowers for pollination. Our famous Rafflesia flower uses this pollination system.

Examples: Carrion feeding scarab beetles (Onthophagus deflexicollis), Carrion flies (Calliphora spp., Chrysomya spp., Lucilia spp.)

Flower structure: The structure of these flowers is surprisingly varied, but they have similar traits of foul smells and dark coloration

 Plants they pollinate: Amorphophallus, Rafflesia, Tacca

References:

Ssymank, A., Kearns, C. A., Pape, T., & Thompson, F. C. (2008). Pollinating flies (Diptera): a major contribution to plant diversity and agricultural production. Biodiversity, 9(1-2), 86-89.


This article is supported by The Habitat Foundation Conservation Grant

Pollinators: Bees and Wasps

Often people ask me about how to make their gardens pollinator friendly. This is a tough question, because there are so many different types of pollinators. Guides usually don’t have all of them in one place.

Here, I’ll explain the categories of pollinators that visit plants, as well as the characteristics of the flowers that they pollinate. But be warned that a lot of the plant examples are not exclusively pollinated by a single pollinator. Often, there can be several different pollinators visiting the same type of flower.

To do this, I dug up a bunch of scientific papers and tried to summarise all of it in simple language here. Some of these categories correspond to categories used by scientists, while some have been simplified and combined for the general public.

Since there are so many pollinators I’ve split this up into a few different articles. This one will discuss bees and wasps.

Bees

Bees collect pollen on their hairy bodies and legs. There are 265 valid bee species in Malaysia. 62 species have been recorded in Kuala Lumpur alone (some of these may be undescribed).  Bees can be divided into two guilds: large bees and small bees.

Large bees

These are your typical bees, locally called lebah or sometimes kumbang*. Only honey bees tend to sting, and only if aggressively disturbed. 

They vary greatly in size, from 10mm to 40mm in length. Large bees tend to travel quite long distances in search of flowers, and due to this prefer flowers with more nectar.

Many of these bees are long tongued bees, they have long mouthparts that lets them suck up nectar that is deep in flowers. A subgroup of large bees are the very large carpenter bees, which tend to prefer larger flowers that can support their weight.

Examples: Honey bees (Apis spp.), carpenter bees (Xylocopa spp.), Blue banded bee (Amegilla spp.)

Flower structure: Usually these are not round and are somewhat tube shaped, often with a petal where the bee can land. However they also pollinate or steal pollen from round, shallow flowers by crawling around inside them.

Plants that they pollinate: tomatoes, eggplants, begonia, Senduduk, Coromandel, many wildflowers.

*In the Malay language, carpenter bees are kumbang kayu, although kumbang is also used for beetles.

Small bees

This is a more diverse group of bees, but easily missed due to their small size (2-12mm). They include bees that live in colonies like stingless bees or solitary bees like sweat bees.

These bees are slower fliers with less range than larger bees. Some of these bees have shorter mouthparts and cannot harvest nectar from very deep flowers. They feed primarily on pollen, and therefore tend to prefer shallow round flowers that they can walk in and collect pollen.

Examples: Stingless bees (Heterotrigona spp.; Lepidotrigona spp.; Tetragonula spp.), Sweat bees (Halictidae)

Flower structure: Shallow round flowers which are not tube shaped.

Plants that they pollinate: Basil, lotus, water lily, Lantana, sunflowers, Beggarsticks,

Wasps

Wasps are less furry and much thinner than bees. They can be identified by their thin “wasp waist”. While many are predatory, they sometimes pollinate flowers when they opportunistically feed on nectar or pollen. However they pollinate with less efficiency than bees because they lack the fuzz to trap pollen.

But there are flowers that are adapted to being exclusively pollinated by wasps, although a lot is still unknown about this type of interaction.

Examples: Hover wasps (Liostenogaster spp.), paper wasps (Ropalidia spp.)

Flower structure: Usually these flowers communicate with their pollinators by smell and taste of nectar (some of which cannot be detected by humans).  Some orchids mimic wasps and transfer pollen as the wasp tries to mate the flower.

Plants they pollinate: Some species of Orchids such as Coelogyne sp., usually these have greenish-yellow colours.  At the moment I can’t find any records of Malaysian plants being pollinated by non-fig wasps. (Any help on this would be appreciated)

Fig wasps

Fig wasps are an example of a keystone species that nobody thinks about. Without fig wasps the fruiting events of figs which sustain most birds in urban settings would not be possible. The reason being that fig wasps are the exclusive pollinator of figs.

Fig flowers grow inwards, forming round structures called synconium. The synconium has a small hole in it that is just big enough for a fig wasp to enter. Female fig wasps lay eggs within fig flowers, while also pollinating the flower so it produces a fruit structure that the larva can feed on. The new females emerge, mate with wingless males, pick up pollen and escape the fig fruit to continue the cycle.

Examples: Fig wasp (Ceratosolen spp.)

Flower structure: Synconium. Flowers that grow inwards and look like round fruit.

 Plants they pollinate: Figs

References:

Cheng, J., Shi, J., Shangguan, F. Z., Dafni, A., Deng, Z. H., & Luo, Y. B. (2009). The pollination of a self-incompatible, food-mimic orchid, Coelogyne fimbriata (Orchidaceae), by female Vespula wasps. Annals of Botany, 104(3), 565-571.

Weiblen, G. D. (2002). How to be a fig wasp. Annual review of entomology, 47(1), 299-330.

Ascher, J.S., and Pickering, J. 2020. Discover Life bee species guide and world checklist (Hymenoptera: Apoidea: Anthophila). Available from http://www.discoverlife.org/mp/20q?guide=Apoidea_species [accessed 8 May 2020].


This article is supported by The Habitat Foundation Conservation Grant

A Beginner Butterfly Garden

A beginner’s butterfly garden uses host plants and flowering plants that grow wild. Shade is not an issue for many of these butterfly species here since they are adapted to living in hot open areas. Because this garden uses wild plants, it requires almost zero maintenance (except for occasional trimming).

For aesthetic value, you can hide the host plants behind or between ornamental plants, or use them as verges (edge or border plants).

Some of these butterfly species may already be present in your gardens. But enriching your garden for butterflies can bring them closer for you to view.

Target butterflies

This garden is suitable for sustaining populations of these species of butterfly.

Passionflower butterflies

These are recent introductions to Malaysia; they can use passionflower vines as a food source for their caterpillars

Coromandel and Cleome butterflies

These butterflies have a variety of host plants but they can use coromandel and cleome as host plants.

Lawn butterflies

These butterflies lay their eggs in lawns on low growing plants that can withstand being mowed.

Roadside tree butterflies

These butterflies can use common roadside trees as a host. This means that you don’t have to plant their host plants but they will still be attracted to your garden.

Host plants

Common four rings use grass as a host plant. A pesticide free lawn is enough to sustain these butterflies

This is the list of host plants that can be planted in a beginner butterfly garden. You can choose to plant all or just some of them. A few of these are common urban wildflowers.

Passionflowers are creeping vines that can be grown on fences. Sometimes they can be found growing on the borders of drains or other plants.

Coromandel and Cleome are two easily grown wildflowers that are almost everywhere and require almost no maintenance. They grow low and won’t take over your garden, so a small patch or planting them between pots is possible. Both these plants produce seed pods that can be easily harvested from patches of wildflowers.

Lawn plants like grasses and some plants that grow together with grasses, such as Semalu and Desmodium, are also used by lawn butterflies.

Target butterfliesHost plant species
Passionflower butterfliesCorky passionflower, Passiflora suberosa
(other ornamental passionflowers can also be used as long as you don’t mind caterpillars)
Coromandel and Cleome butterfliesCoromandel, Asystasia gangetica (ornamental varieties are available if you would like to use them instead)
Purple Cleome, Cleome rutidosperma
Lawn butterfliesSemalu, Mimosa pudica
Desmodium
Goat grass, Ishaemum muticum
Roadside tree butterfliesAcacia
Raintrees, Albizia
Cassia
Desmodium is a host plant for the Tiny Grass Blue butterfly. It also enhances soil fertility and can grow in between grass in a lawn.

As with wildflower patches, allowing other plants to grow in between the host plants helps to fertilise the soil and lower the need for maintenance. Let it grow wild without pesticides and you might get additional biodiversity such as stingless bees and ladybugs.

Flowering plants

Little ironweeds can survive in degraded land and are very attractive to pollinators

Coromandel flowers can double as a nectar source for adult butterflies. Easily grown wildflowers such as Goat weed, Cupid’s shaving brush, Tridax daisy and Beggarticks are suitable sources of nectar since they are almost always flowering.  Since all of these are from the sunflower family, they produce dandelion like seeds that reseed the plot after the wilt.

The seeds can be harvested from wild patches and placed in a plot.

Tridax daisies are hardy plants that are used by a wide variety of pollinators

This article is supported by The Habitat Foundation Conservation Grant

Butterfly Gardens: Key Concepts

Butterflies are nice to have in a garden, they help to make it feel alive with colour and movement. They also become food for birds and carry out important pollination of plants.

To have butterflies in a garden, you have to meet the requirements of butterflies. In no particular order, the requirements are: host plants (for caterpillars), flowering plants (for adults) and suitable amounts of shade.

Host plants

These are plants that caterpillars feed on before they become butterflies. Many butterflies have specific host plants, while some common species have a variety of plants that they can feed on. Sometimes the host plants of butterflies are plants that we eat or use for decoration.

coromandel and pollinator
Coromandels are host plants for many urban butterflies

If you are preparing a butterfly garden, please tolerate a few chewed up leaves. Natural predators like wasps and birds can help to keep caterpillar numbers manageable, so preparing habitat for them too can help to bring a balance to your garden.

Flowering plants

butterfly feeding on Bidens alba nectar
Allowing wildflowers to grow in your garden is a good way to ensure a consistent source of nectar for butterflies

Plants which regularly flower are very attractive to butterflies. These flowers are not necessarily big, but they usually occur in clusters that the butterflies can walk across.

Wildflower patches are a simple way to make habitat for adult butterflies to feed, although edible plants such as Ulam raja and some ornamental flowers such as Lantana, Ixora and Saraca are attractive to butterflies as well.

butterfly and a cluster of flowers
Clustered flowers are very attractive to butterflies

Shade

Butterflies are cold blooded creatures, so they control their body temperature by exposing themselves to sunlight. However, too much sunlight can be harmful to them. Many species of butterflies prefer shadier conditions where they can rest and cool off. Some forest butterflies never leave the shade of the forest, while open area butterflies can tolerate intense heat from the sun. 

Keeping these three things in mind will help make your garden a suitable habitat for butterflies. However, you can meet the requirements of some species of butterflies and still not get a desired species. This is because butterflies have to get to your garden, and usually, species that are more sensitive to urban environments may need pathways from forest patches that they can safely migrate through. So it is good to keep in mind that connectivity to forest patches is a good way to ensure that butterflies can establish themselves in home gardens.

If you want to experiment with these concepts, you can try planting a beginner butterfly garden that attracts very hardy urban butterflies.


This article is supported by The Habitat Foundation Conservation Grant

See also

Rewilding, the case of urban Birdwing butterflies

Here I explain how you can think about ecosystems and how to restore them. The case study of the Golden Birdwing Butterfly, which can be found in the urban forest patch that is Rimba Ilmu Botanic Garden located inside the University of Malaya.

Merely reintroducing a species does not produce long lasting results. Butterfly farms all over the country constantly have to restock wild caught butterflies due to captive butterflies dying and not reproducing. When an animal is placed in a system that does not meet its needs, there’s nothing much that it can do except go extinct.

The secret to the birdwings survival is the fact that it has a functioning ecosystem that produces resources can satisfy its ecological requirements.

In a butterfly farm, the basic requirements for survival are met; the temperatures are suitable and there is enough food supplied through cut flowers and fruit. The ecosystem in a butterfly farm looks like this:

To be more sustainable and reduce the cost of having to feed the birdwings, you could plant food plants for the birdwings, so they can feed on the nectar. Birdwings prefer flowers that grow on in large clusters like Saraca, Ixora and Bauhinia kockiana so they can walk along and feed. The ecosystem would look this this:

As mentioned before, once the end of the lifespan of the butterfly is reached the ecosystem collapses. This is because all butterflies require a host to develop on as a caterpillar, in this case the Birdwings are breeding on a climbing plant known as Pipevine (Aristolochia tagala). If supplied with a host plant, the butterflies can lay their eggs and reproduce and create a new generation. This ecosystem would look like this:

However, Birdwing caterpillars damage the stem once they are about to pupate into a butterfly. This behaviour is believed to increase the nutrient density of the leaves while reducing the water content. Because of that, the above ecosystem will also eventually collapse after enough caterpillars damage and kill off all their hosts.

The special thing about the Rimba Ilmu ecosystem is that it has pollinators for the Pipevine, so the Pipevine can reproduce and replace the population that is lost to caterpillars. What is the pollinator of the pipevine? Tiny flies (Drosophilla spp., Megaselia spp.), which get caught in trap chambers in the flower of the Pipevine and forced to become pollinators without any reward. So a more viable ecosystem looks like this:

Of course since the Pipevine doesn’t feed them for the service of pollination, the fruit flies require their own food source, which is often rotten fruit, decomposing materials or fungus. These decomposition systems happen when there is enough fallen fruit, mulch and rotting logs in the overall ecosystem. This is supplied by leaves, fruit and branches falling off the plants in the system (which is an important reason to always leave some decomposition around). This results in this ecosystem:

The example above is a functioning, self sustaining ecosystem. As long as it gets enough sun it can keep going without any human interference. But the most interesting thing about this ecosystem is the fact that it assembled itself. While this “let nature find a way” approach is possible, we can help it along by being aware of the different parts and the needs of each part of the system. If you want butterflies in your garden, you need to think about more than butterflies.

References:

http://rainforest-australia.com/birdwing.html


This article is supported by The Habitat Foundation Conservation Grant