Occupation:
|
Predator, pollinator
|
Value
to Gardener:
|
5/5 - Pest Controller and Pollinator
|
Danger
to Humans:
|
2/5 – Most are harmless, some bite
|
Availability:
|
5/5 – They’ll arrive or you can buy some
|
 |
| Basic anatomy of a fly Culex pipiens mosquito |
Quick Intro
Flies are seen as vermin and disgusting creatures. Although a
large portion of flies are detrivores and parasites, most are active predators
and excellent pollinators. Fly predators eat a large range of pest species and
the pollinator species are valuable when bees are lacking.
Science Stuff
Flies belong to the order Diptera (Greek, di = two and ptera = wing)
and includes crane flies, midges, mosquitoes and various fly species. Some
species mimic bees in appearance, such as hoverflies and bee flies, and are
important pollinators. This often leads to confusion between the two orders;
therefore I again provide my little diagram to illustrate the difference
between Hymenoptera (Bees, wasps and ants) and Diptera (Flies and mosquitoes).
Hymenoptera have a narrow waist, whereas Diptera have their hind wings reduced
to spoon-shaped halters used for balance in flight. Strepsiptera
(twisted wing parasites) have the opposite, their forewings are reduced to
halters and their hind wings are used for flight.
Flies have large diverse niches, making use of all nature’s
resources by being parasites, detrivores, fruitivores, pollinators and
predators. Mouthparts vary from piercing-and-sucking to only a sucking
proboscis. Chewing mouthparts are in some blood-feeding species. There are too many
fly families to discuss, therefore, I will cover some of the more ‘garden’
important species:
Tipulidae (Crane flies, daddy longlegs, and leatherjackets):
These are large, spindly flies with very long legs. They do not fly well and
some are wingless. Larvae, known as leatherjackets, live in water or moist
soil. Larvae feed on plant roots and may be destructive, whereas adults never
feed. Example specimen in the diagram above.
Culicidae (Mosquitoes): Best known for their blood-feeding (haematophagous)
lifestyle and for transmitting diseases such as malaria, dengue fever,
encephalitis, yellow fever and elephantiasis. In some species, both males and
females feed on plant juices, in others, females need to take a blood meal in order
to lay eggs. Males and females look identical, except males have bushy antennae
to pick up on the buzzing sound of the females.
+Os+Mosquitos+no+Par%C3%A1.+Memorias+do+Museu+Goeldi.+Wikipedia.jpg) |
| Aedes aegypti mosquito male (right) and female (left) Notice feathery antennae of male |
Cecidomyiidae (Gall midges): Small, hairy flies that go mostly
unseen. These flies will infest a specific host, to which they have evolved, through a process known as co-speciation. They cause galls formation on host
plants. Adults are short-lived, whereas larvae are pests of millet, sorghum and
rice.
 |
| Gall midge sp. Cecidomyiidae |
Tabanidae (Horse flies, clegs, and deer flies): Sturdy flies
often with iridescent eyes. Both males and females feed on nectar or plant juices,
but females are also blood-feeding and inflict very painful bites. The females
transmit surra or nagana to cattle and horses respectively, similar to sleeping
sickness in humans, and also transmit the Loa
loa eye worm to humans and monkeys.
 |
| Horse fly, Tabanus sp. Tabanidae |
Asilidae (Robber or Assassin flies): Their robust build and
prominent proboscis makes them easy to recognise. Many are hairy, aggressive and
quite frankly scary - with an equal reputation as voracious predators of other
insects. Adults are strong and agile fliers. Most larvae feed on detritus.
 |
| Robber fly with stink bug, Tessaratoma papillosa prey |
Bombyliidae (Bee flies): Stumpy flies often covered in fuzz.
They have long sucking proboscis and are important pollinators of many plant
species. They bask in the sun and are active during the hottest part of the
day, common in dry climates. They are graceful fliers and can rival the hovers
in, well, hovering. Larvae are predators of insects or eggs.
 |
| Bee fly, Bombylius major Bombyllidae |
Syrphidae (Hover, Flower or Syrphid flies): These are the bee
and wasp mimic specialists, all with black and yellow striped bodies – remember
to check for the narrow waist when in doubt! They have an astounding precise
suspended flight (hover) and can zip about quickly. Adults feed on nectar and
pollen. Larvae occupy many different niches; some are predaceous on plant
pests, whereas others (known as rat-tailed larvae) feed in mud, and every niche
in between.
 |
| Hover fly |
Tephritidae (Fruit flies): Easily recognised by their long ovipositor (egg laying organ), triangular heads and patterned wings. These flies are host specific and adults deposit eggs in important agricultural fruit plants. Larvae develop inside the fruits and feed on the flesh. Be watchful as some have ‘narrow’ waists, but look out for the halters, they are a dead give-away!
 |
| Fruit fly Euaresta aequalis Tephritidae |
Habitat
Flies have diverse habitats and are common everywhere. Some
larvae live in water, others on plants and some are soil-borne.
Robbers prefer to hunt in fairly open areas with little
vegetation, so you will likely have them visit the garden rather than take up
refuge.
Hovers are attracted to plants under attack by aphids - plants
emit certain volatile chemicals when fed upon by pests that the hovers hone onto. The adults will buzz around the affected plant and promptly lay eggs on
the leaves. Eggs hatch and the aphid-eating army munches away!
Bee flies? Just plant a basil – they loovvee the basil
flowers! Provide some open areas in the ground or in your pots where they will
make little burrows to overnight in. You will also notice that the bee flies
make a lot more buzzing noise than bees. My garden is residence to many Woolly
bee flies (Systoechus spp.) and they
are adorable!
.JPG) |
| Woolly Bee Fly Bombyliidae, Systoechus sp. |
2.JPG) |
| Woolly Bee Fly Bombyliidae, Systoechus sp. |
Robbers
ambush bees, wasps, hornets, spiders, grasshoppers, other flies and many species
of flying insects in flight. It stabs its prey with their short, strong
proboscis. They inject neurotoxic (paralytic) and proteolytic (protein
degrading) enzymes into their victims, and subsequently suck out the digested
liquids – very gruesome!
+Wikipedia+2.jpg) |
| Robber fly sp. The 'moustache' or mystax and occular fringes are visible in this species |
Lots
of small flowers, such as those from the Compositae or Asteraceae plant family
(dill, fennel) will convince the adult hovers to stick around. The two regular
visitors to my garden are, Allograpta
fuscitibialis (I will refer to it as the Black thorax hover fly, due to a
lack of a common name) and Eristalinus
tenax (which I will just call the striped-eye hover fly).
 |
| Black thorax hover fly Allograpta fuscotibialis |
 |
| Black thorax hover fly Allograpta fuscotibialis |
 |
| Striped Eye Hover Fly, Eristalinus taeniops |
 |
| Striped Eye Hover Fly Eristalinus taeniops |
Flies – last thoughts
Flies
are unfairly defined as gross and need to be exterminated when the majority are
misunderstood and beneficial to gardeners as predators of pest species and
important pollinators. Seeing as they are so freely available, they make great supplementary
pollinators (to bees) and effective biological pest control.
Do you have any pollinator or predatory fly visitors to your garden?
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