Dung-flies and rat-tailed maggots

Posted: Friday 13 April 2012
by Kate Bradbury

Apparently there’s nothing like a foul-smelling bucket of leaves to get dung-flies going...

Making nettle feed

Every year I make organic solutions from nettle and comfrey leaves to feed my plants. Nettles make a good nitrogen-rich feed for leafy crops like brassicas, while comfrey leaves are rich in potassium, making them ideal for feeding tomatoes and peppers. Making the feeds is easy – simply steep the leaves in a bucket of water for two weeks, then use the solution (diluted roughly one part feed to 10 parts water) when watering your plants. You can use it all immediately, bottle it up to use later, or leave it in the bucket until it becomes a foetid, stinking mess, like I do.

Apparently, there’s nothing like a foul-smelling bucket of leaves to get dung-flies going. It seems that, when the stench of the solution becomes almost unbearable to the human nose, suddenly hordes of these little orange insects descend on it for some sort of mating fest.

Last year I spent a good half hour watching dung-flies mating in the bucket of nettle leaves which, presumably, had taken on the aroma of excrement (it certainly smelled that way to me). They normally breed in horse or cow dung (but are not averse to the droppings of cats and foxes), so I’m not sure how productive the nettle orgy was. This year, I intend to find out.

I’ve made two buckets of nettle solution – one for the plants and one for the dung-flies. I’ll make the effort to bottle up one of the solutions in two weeks’ time, which will be diluted and used when watering leafy plants in summer. The other bucket is in a corner, as far away from the back door as possible, where its contents will be allowed to fully decompose and give off that alluring aroma of ... dung.

Reading up on the lifecycle of dung-flies, I can’t see how a bucket of nettle water would really meet their needs, as the females prefer to lay eggs on the surface of dung to prevent the emerging larvae from drowning. With this in mind, I've adapted the second bucket to avoid unnecessary dung-fly death. I’ve stacked soil in the bucket next to the nettles and used less water, so its contents has the consistency of muddy soup. Hopefully the smell will still attract the flies, but the larvae will have a better chance of surviving.

I’m hoping my bucket of 'eau de stinking nettle' will also attract some species of hoverfly, including Myathropa florea, which traditionally breed in soggy decaying matter, such as rotting tree stumps. I once saw one laying eggs in my compost bin, so my bucket of muddy nettle sludge should be just the ticket. I'm ever hopeful that, as well as having my own pet dung-fly larvae, I'll also have a collection of rat-tailed maggots. My neighbours are going to love me.

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Talkback: Dung-flies and rat-tailed maggots
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happymarion 13/04/2012 at 15:46

Good idea, Kate. My nettle patches are growing strongly now so i should be able to harvest some and leave the rest for the caterpillars till I cut them in June. I saw my first Speckled wood butterfly this morning - near my potting shed which is the back half of the garage. It must have overwintered there and I leave the door open during the day while I am home now so that the ladybirds can come out and any overwintering butterflies.

oldchippy 13/04/2012 at 22:17

Hi Kate if it smells that bad I think I will give painting your flat a miss ,I don't think I would like living near you.


kevc 14/04/2012 at 07:10

ok so what is the perpose for dung flies and rat tails maggots allso what is the best way to solve reallly bad wet clay soil Ive tryed sand

what sort of shrubs can I grove in this bad soil

kaycurtis 15/04/2012 at 04:35

Well Kate if you can manage to stay watching these things mating for half an hour you must have lost your sence of smell yuk! I happily haven't lost mine.

Kate Bradbury 16/04/2012 at 10:23

Thanks for all your replies.

@happymarion - how lovely. Sounds like you have the perfect butterfly- and ladybird-friendly garden.

@oldchippy - the nettle bucket isn't in the flat! The smell isn't that bad, really. I can guarantee you won't notice it if you come to paint it ;)

@kevc - dung flies are important predators of other flies, including mosquitoes, and rat-tailed maggots turn into hoverflies, which pollinate flowers and fruit and veg crops. But why do they need a purpose? What purpose do humans have? Regarding your clay soil, if you give it a really good dig over, then dig in some horticultural grit, you should notice a difference immediately. Then, every spring and autumn, apply a mulch of home-made compost/well-rotted manure. This should make the ground more manageable.

@kaycurtis - the smell isn't so bad, really, and you soon get used to it. It's fun!


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