Insect Pests in your Worm Beds

Worm Composting...

One topic that comes up a lot, both on the forum and in the questions received, is worm bed ‘pests’. Of course this is totally understandable – we all want our worms to stay healthy and happy, and thus invaders of any kind can easily cause us alarm.

That being said, in my experience the stress associated with unwanted bin/bed creatures tends to be more pronounced in those who are just getting into worm farming/composting.

After you have been at it for a number of years you definitely start to mellow out a lot more as you realize that many of these bin creatures are perfectly harmless or even helpful. It also depends on what your main purpose is. Are you trying to raise fat bait worms, or are you simply interested in processing organic waste and producing your own worm compost? I fall into the latter category, which might explain why I’m even more mellow than many. 🙂

All the same, there are definitely some pests that can be pretty annoying (for us) or even downright dangerous for your worm population.

This week we’ll chat about a couple varieties of insect pests: ants and flies.

The issue of ants invading worm beds seems to come up quite a lot, and in fact I experienced my own ant invasion when I first set up my large out door bin. Up here in the north, where ants tend to be relatively small and harmless, a minor ant invasion is definitely no reason to panic. They are simply attracted to the food in your beds and won’t likely cause your worms any harm.

In more southerly zones however, larger/more aggressive species, or those with venom (such as fire ants) can certainly inflict more harm on the worms themselves.

Thankfully, most ant issues result from worm beds getting too dry during summer months, and can be resolved by significantly boosting moisture levels. To help retain moisture in your outdoor bins you can 1) Move them in shady areas 2) Line them with cardboard (only really necessary if there are significant air spaces) 3) Use a thick layer of straw or shredded paper over top, and of course 4) Add water fairly regularly.

I definitely would NEVER recommend getting rid of ants with any sort of nasty chemicals – you’ll just end up potentially harming a variety of other creatures (potentially even you and your family).

If your property is particularly infested with anthills you might want to try an easy (yet effective) technique I recently learned on the Worm Digest forums (in fact, one of our prominent members, WFike, offered the tip) – simply pour a pot full of scalding hot water into each anthill. This will flood out the nest and of course the hot temperatures will kill most of the inhabitants.

Ok, moving on…

Various flying insects can become serious worm bin annoyances if proper measures are not taken to prevent infestation. The two major offenders I’ve dealt with are fruit flies and fungus gnats.

Both are similar in size (very small), and both are incredibly prolific breeders, producing dense clouds of tiny adults in a very short period of time if left to their own devices.

Luckily, neither species poses any real threat to your worm bed (more of an annoyance than anything), and preventative measures will go a long way towards reducing their success.

In the case of fruit flies, the worst thing to do is leave any fruit/veggie scraps you have out in the open for an extended period of time, whether it be on the surface of your worm bin/bed, or in your kitchen scrap holder. This is just an open invitation for fruit fly colonization.

Also, keep in mind that there can be fruit fly eggs already laid inside various fruit peels, so it never hurts to microwave or freeze these material prior to use if you are really serious about preventing colonization.

Maintaining a thick layer of bedding material (straw and shredded paper/cardboard work well) over top of your waste materials is another great way to suppress both fruit flies and fungus gnats, especially for lidless systems. This makes it much more difficult for the adults to swarm and mate and just generally keeps them out of your face.

Even if you already have a bad infestation of either of these pests, adding a decent amount of new bedding over top should help to improve the situation considerably.

Both of these small flies tend to go through ‘boom and bust’ cycles so be assured that even the most serious of infestations will pass.

There are SOME other fly-like insects that can invade your worm bin, especially those located outside.

In general, house flies will only invade a bin if there is rotting meat inside (and hopefully you know better than to add meat to your bin!). In warmer regions, soldier flies can also invade worm beds and compost heaps. The larvae of these insects are actually great waste processors and some people even raise them specifically as a food source for fish/chickens/reptiles.

As is the case with most flying pests, keeping a lid and a thick layer of bedding over your waste materials at all times can help a great deal.

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  1. One of my outdoor bins did get ants. I scattered a small handful of dried mollasses in the bin. The ants were gone in a matter of hours. They do not like mollasses. In the future, I will only add the mollasses if I see ants.
    They did not invade the other 2 bins, so those went untreated.

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