Rotting

So when my ever-resourceful wife first decided to try out composting, we lived in an apartment with very little outdoor space - a long, narrow balcony that was used a lot by our toddler.  She spent a bit of time researching in-kitchen type systems, and in fact found one that looked like it would do what we needed: a product sold by a local company that consisted of a small plastic bin with a tap at the bottom for the junk juice (apparently they call it 'leachate'), and some packets of powder that needed to be added to the food waste inside to help it break down.

The perfect birthday present, I thought.  So I bought one, and we tried it out. It worked a treat!  Until the bin got full. Then the instructions required burying the half-rotten waste in the ground for a period of time.

Except we had no ground to bury it in.

And the idea is that you kept buying the little packets of stuff to keep adding with the food waste.  Which gave me feeling about this which reminded me of how I feel about cheap printers and expensive printer cartridges...

...and coffee pods...

My sister-in-law volunteered to bury it in her garden, and collected two loads of putrid kitchen waste, before refusing any more because the smell was so bad she couldn't stand it any more.

The special bin with the tap fell into disuse, and didn't make it through the move when we went to live in a different apartment a year or so later.

The apartment we moved into is in a much smaller building. There's no balcony, but we have access to the terraza - the roof area of the building, which is officially shared by the four aparments in the building, but which informally the half above our apartment is ours to use and maintain, and the other half is for the other upstairs apartment.

As the roof leaked, one of the first things we did after moving in was resurface the terraza.  In New Zealand, house roofs are generally corrugated iron or tiled. Apartment buildings have a concrete roof.  In Argentina, it turns out, the concrete roofs are waterproofed with tar and then covered with membrana to protect the tar.  Membrana is a kind of metal foil which is usually painted with waterproof paint, to add to weatherproofing and eliminate dazzling reflections. But it's all pretty fragile, actually.  You can walk on it, if you're careful, but putting chairs and tables on it for pleasant outdoor sitting in summer is an invitation for rain inside your house in winter.  So we resurfaced our half of the roof with a reinforced membrana that won't leak when the girls run around, fall, and generally do crazy stunts on the roof.

We started to fantasise about having some kind of rooftop garden, or even a green roof! No, maybe not a green roof, because it would probably collapse into our living room...

Anyway, long story short, we now had a bigger outdoor space, wanted to have at some point plants or maybe small trees.  Could we make composting work? And then use it for the plants?

We did a bit of googling, found various products and systems, considered maybe worms... The general recommendation seemed to be that it could be done in a plastic bin, with drainage at the bottom for leachate, ventilation holes, and protection from rain.

Problems: 

• Our neighbours would probably hit the roof if they discover we have worms as pets 
• The list of things you can and can't compost, and the things you have to do to keep it going, make it seem pretty complicated
• We don't want junk juice leaking all over our terraza
• There's nowhere protected from the rain
• In our first summer, we found ourselves waging war against an invasion of cockroaches - we more or less won the war, and don't want the roaches coming back, attracted by delicious smells of putrifying kitchen waste
• One night there was a rat outside our bathroom window - we never saw it again, but rats are around, and we don't want to attract them

It seemed hopelessly impractical.

But my implacable wife persisted in her investigations, and discovered proponents of "no rules" and "extreme" composting; people who say "chuck it all in, let it rot, and let's not be too precious about it".

So she cleaned out the plastic paint containers left after the roof-resurfacing, and started throwing our kitchen waste in it - orange peel, vegetable off-cuts, coffee grounds, etc. And some cut up paper and some dry leaves. And some soil as well.  The first bin had some holes poked in it for ventilation, but there's no drainage for leachate, and we put the lid on tight to keep rain, roaches, and rats out.

It worked out pretty well, actually; within a few weeks, adding to it daily and giving it the occasional stir up, we had a bin filled with what looked like wet soil.  Still a bit smelly, but not too bad.  We started on a second bin (no ventilation holes this time, but opened daily and stirred to get oxygen in there.  It's pretty smelly when you take the lid off, but seems to be putrifying away ok.  Meanwhile, the compost in the first bin was reducing down and drying out.

Before too long, we had a chain of bins at different stages.

Great!  We're making dirt, and I don't have to take out a rubbish bag every night any more, we go two or three days before our tiny paper rubbish bag needs taking out!

The girls bought me a small lime tree for Xmas, and our idea is to generate the soil to plant it in, and then maybe next summer or the one after, I'll be sipping lemon, lime and bitters on the terraza on balmy evenings.

I was rudely awakened from this dream the day we found a tiny wriggly larva in our second bin. I gingerly probed under the surface, and found a handful more (not a literal handful, as there was no way I was going to touch them with my hand; I mean 4 or 5).  Within a few days, the bin could be described with only a little exaggeration as a "writhing mass".  Our compost has maggots!

Eww!!

We couldn't quite understand it.  I thought maggots basically ate meat, which we weren't adding to the compost (we tried a bit of cheese rind once - very stinky!). And there weren't any visible flies. And the lid was basically always on.

Back to the internet. It turns out that these were most likely not house-fly maggots, but rather "Black Soldier Fly" larva. They like all food waste - meat, yes, but also veges and fruit, and even animal poo!  In fact, Black Soldier Fly larva (or BSFL as they're affectionately known) have quite a fan base on the internet, where there are numerous photos of literal handfuls, and lots of people cultivating them on purpose.  They even have their own blog - blacksoldierflyblog.com!

Apparently they're quite good for composting, although it can be a sign the compost is too wet or "green", and they seem to be competition for worms, for those who have them.  Who knew!? I assumed they weren't exactly the same fly as the one all the North Americans were talking about, but rather some equivalent Argentinian bug. But presumably similarly beneficial? Maybe?

All right then.  We soldier on, adding daily kitchen waste, with a slightly higher level of disgust than before, but also with determination.  We may be squeamish, but can make this work!

Then, disaster.  I arrive home to my terrified wife telling me that she opened bin number one and out flew AN ENORMOUS BLACK WASP!!  Wriggly maggots is one thing, big dangerous sting-y wasps is quite another!

That, right there, was the end of the compost; the girls play up there, we hang the washing there every day.  I'm mortally allergic to bee and wasp stings.  We cannot have wasps emerging from our compost!

But...

Just to be sure it really was a wasp, I googled "what is this bug", which led me to the bugclub yahoo group. I sent the photos my horrified wife had taken to the group, asking if it was likely a wasp would be coming out of our compost.

Then, while waiting impatiently for an answer from the bugclub brains trust, I had a thought I should have had several days before:  larvae turn into bugs. Having things fly or crawl out of the compost is inevitable, if we have larvae in there. So we'd been relieved to find out that our 'maggots' weren't from house flies, but hadn't bothered to find out what these Black Soldier Flies look like... duh...

Wikipedia and other sites describe them as being wasp-mimics, which can be almost an inch long - i.e. "enormous black wasp" is a pretty good description.

By Gee W. at English Wikipedia, CC BY-SA 3.0

Do they actually live in Argentina anyway?  Well, on the BSF Project's map, there are no wee maggot icons on Buenos Aires, but there are on Montevideo, which is just across the river.

Then, a BSF vote came in from bugclub.  Ok, so probably it's just the fly we should have been expecting all along.

But my my squeamish wife wants NOTHING TO DO WITH ENORMOUS BLACK WASPISH BUGS!  So I spent the night googling for ways to get rid of BSF.

It turns out that it's pretty hard information to come by, because everyone wants to attract, foster, and breed them.  It turns out that:

• the larvae and adults flies are harmless
• they make compost faster than worms
• they keep house flies and blowflies away
• the adult flies have no mouth, so don't go into houses and vomit all over food like house flies do
• they reduce the amount of e-coli and salmonella in poo
• chickens and pigs love to eat them

However, I did discover that, in addition to their appearance in compost meaning it's too wet (so adding more paper and leaves would presumably get rid of them), also supposedly adding lime keeps the flies away, so there are no eggs laid.

My disillusioned wife made me promise to go buy some lime the next day, which I did.

But the more I thought about it, even though larvae and flies are yucky, it seems like a shame to get rid of them!  I don't want to see them or touch them, and god forbid our neighbours find out about them. But basically they're doing what we want - reducing our food waste to compost we can use to grow limes for my cooling summer drinks!

So when I presented my insectidal wife with 2kg's of promised lime, I also presented my argument for humouring our wriggly friends a little more, and volunteered to take on all rooftop compost duties, so she wouldn't have to risk the willies any more.

She reluctantly agreed.