How to get rid of maggots & flies in compost?

13 April 2012  |  HOTBIN Composting

A HOT HOTBIN will prevent and/or kill maggots and flies

The HOTBIN should not have any flies or maggots inside. 99% of customers state they are satisfied or very satisfied with how the HOTBIN reduces and prevents flies.

However, in certain circumstances flies and maggots can occur in the HOTBIN. Below we outline how this happens and more importantly how to get rid of them quickly and stop them reappearing.

House flies and fruit flies (aka vinegar flies – the tiny little ones) will eat food waste and lay eggs in ANY/ALL food waste or exposed compost. They can lay eggs in the waste anywhere from the kitchen, kitchen caddy / bags holding waste and possibly at any time when the lid is open or the door is not fastened tightly. Your HOTBIN has a tight fitting lid and door. Always ensure they are tightly closed. Flies are unlikely to enter when you are tipping in waste.

In a ‘cold’ normal compost bin, the eggs in the food hatch into maggots (you can see house fly maggots, but not fruit fly ones) and eventually a fly or in extreme cases a swarm of fruit flies exit when the compost bin lid is taken off.

In a correctly operated HOTBIN, once the heat gets above 40C, all creatures (except thermophilic bacteria) will die off. As soon as the temp rises above 30C, you start to see an exodus – some creatures (crawling ones) migrate down to base of bin, the rest try to escape up the walls towards the lid. As the lid is closed they are trapped. As soon as the HOTBIN starts to get above 40C they die off - within days at 40C, within minutes at 60C.

A HOT HOTBIN will prevent and/or kill maggots, flies and fruit flies.

Now here’s the tricky bit – when you start the HOTBIN it’s cold, it warms up to 20-30C. At 30C this is the perfect breeding temperature for flies. If your HOTBIN ‘sticks’ at this temperature and your waste had eggs laid in it before adding into the HOTBIN - you will get a fly problem.

You need to ensure the HOTBIN gets hot – once hot, within a few hours NO maggots or fly issues. If you have flies it is an absolute indicator you are not Hot Composting yet.

The basic control of flies in HOTBIN is down to two key items:

  1. They can’t get in and rarely will enter via the open lid if you are present
  2. If they have laid eggs on waste before it was added to the HOTBIN, as soon as the HOTBIN gets above 40C they will die and not hatch.

If you have flies it is an absolute indicator you are not HOT Composting yet.

How do I get rid of them?

Easy – Get the HOTBIN HOT and the next time you add waste, there will be no flies inside the HOTBIN.

Please re-check the ‘how do I get to 60C check list

Please consider the following fast but very quick and effective cheats to get your HOTBIN to 60C:

  1. Adding a box of grass mowing and mix them into the waste already in the HOTBIN
  2. If no grass, add 2-3 cups of either chicken pellets or chicken poo
  3. Check excess water is not seeping from aeration/mesh in base - if it is, add half a bucket of cardboard pieces and half a bucket of wood chip (from black bag)

NOW Stand back and give it 72 hours - it should race ahead to 60C, and all flies will be composted in about 2 days time..

Please note: you might occasionally have flies hovering around the valve or crawling on the door hatch panel. We can’t stop this. There is always some residual odour around the valve, and often some old compost on the door. They normally give up and move on when they are unable to find the food source that generates the odour i.e. they cannot find the place to eat and lay eggs.

If they bother you and you are not adverse to using chemicals, then any of the fly/crawling insect sprays can spayed on the HOTBIN parts to keep them away – but outdoors this is a bit of a losing battle – it will wash off in the rain quickly. But do try to keep the area free of dropped food & compost.

If you are still "Struggling to get your HOTBIN hot" please check this post.