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I have an ant infestation in my garden. Whenever I water my containerized plants or in-ground plants, most of the time, ants emerge to the surface. I think they do that because they don't want to drown. First of all, do ants cause problems when they dig near your plants. If so, how do I get rid of them? I've sprayed Raid on my containers, but they keep coming back.

Here's an example of the ants emerging from my blackberry plant. This time in particular, each of them was carrying something white. Most of the time, they're not carrying anything.

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  • It's hard to see the ants in that pic. – J. Musser Aug 30 '14 at 16:37
  • You can see the white specs that they're carrying more easily than the ants themselves. Do you see that really big circular-ish mulch chip? There's three ants on top of it. Then if you follow those upward-leftward you'll see dozens of the same thing. – JoJo Aug 30 '14 at 17:27
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Not too much of a problem in open ground, but they certainly can be if they're nesting in your containers or pots. They don't eat plant roots, but they can and do break them up in order to extend their nest within the container. If they're already in there, you need to take remedial action, the first part of which is to thoroughly soak the pots to encourage the ants to leave before you start. Then the pots should be emptied out, the plants decanted and inspected to make sure there's no nesting ants within and set aside temporarily, preferably into something with water in the bottom to stop them drying out. You may have to wait for the ants to disappear before proceeding - usually, when they appear after a dousing of water carrying white things, those are eggs, and they're moving them to keep them from being drowned or wetted too much. If they have eggs, they will be panicking and trying to rescue them from your piles of cast aside potting medium, and soldier ants will be looking to punish the cause of this disruption - even in the UK, ants can give painful bites.

The next thing is to refill your pots, but put a layer of something like a Jey cloth in the bottom first, across the exit holes, or a piece of weed membrane fabric, then add the potting medium, replant the plants and, most important of all, stand the pots on something. Anything, pot feet, broken bits of slate, half bricks, anything that raises them off the ground a bit. This should prevent any further invasion into your containers - dusting beneath the containers with ant powder occasionally does no harm either.

  • For the in-ground plants, I've been transitioning to once-per-week deep watering, partly due to California's drought and partly due to my time management. It seems like that wasn't enough to flush out the ants. They emerge week after week. – JoJo Aug 30 '14 at 17:59
  • @JoJo - that sounds like a good watering regime for your plants though. You could always use the old fashioned method of boiling a kettle, opening up a nest and pouring boiling water into it, but you'd need to be careful not to scald plant roots or leaves. – Bamboo Aug 30 '14 at 18:09
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Most species of ants generally don't cause a problem in gardens. They do tunnel, and if too excessively there can be trouble, and they can farm aphids on your plants, and protect them from possible predators. But on your plants, I don't see that they're an issue. They will clean up fallen fruit, if any, eat some bugs (mostly the herbivorous bugs), and generally not be a problem. They tend to nest where it's dry, so if they seem to be more concentrated under your plants, they may be too dry.

If the ant populations get out of control, you can use pyrethrum, or if you don't mind chemicals, something like Carbaryl.

Here's an article that has relevance.

For most species, control is only necessary in the garden if the population gets out of hand. Garden varieties do not actually eat plants or actively destroy any plant matter. Their main source of food is sugar, usually found in nectar, sap, or the honeydew excrement from aphids. In some cases, garden ants can actually be a beneficial insect as they will kill off more destructive pests like caterpillars. They are also natural soil aerators through their extensive tunneling systems. As food for beneficial animals such as birds, lizards, and toads, they will also encourage wildlife to flourish in your garden.

No matter what types you want to reduce, the control methods are similar. As any species can hurt plants by mining nests around roots, if they are excessive in your garden, you will want to reduce the population. They are most problematic to new plants with young roots and lawns. In lawns, you know they are present when you see nest mounds that smother the grass and create unsightly patches. An easy solution to this problem is to grow your grass longer to hide the patches and live with the ants. If this is not your preference, you will have to treat the nests.

In addition to their nesting structures, they have another characteristic that can quickly create a problem in your garden - farming other insects. Certain varieties actually farm aphids for their honeydew. This can quickly create a rather significant aphid problem in your yard as the ants will kill off their natural predators.

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