I have a fairly large glass enclosed plant terrarium that I have had for 6 years. I have needed to water in once when I moved and it needed to adjust to its new home. Over the past 2 weeks a colony of ants have moved in and even have eggs on the side of the glass. I have tried dusting with food grade diatomaceous earth but to no avail. I sprinkled cinnamon all around the terrarium but they won't move out. Any suggestions?

Hi and welcome to NGA!

Do you know how they got in? It would help to see a picture of the whole terrarium as "large" can mean many different things. Your best bet is probably a spray insecticide. If it's really large then perhaps a granular insecticide. You could also get some of those plastic ant traps with bait in them - make sure it's got fiprinil.

The DE does work on ants but it's not quick. Also if you can, remove all the eggs you see to keep the population down. If you can find the queen, removing her would help. You'll also want to plug up any holes as well.

Insecticidal Soap kills ants on contact.

Daisy is right, but I don't think it's a good idea to put it in a terrarium.

My terrarium is maybe 3G. So not huge but not a tiny ball. I have 3 smaller ones on either side as well and the ants do not seem interested either of them. I live in a sandy wooded area so ants have always been a problem come spring and summer.

Very nice! considering how deep the soil is, I'd try some of those baited ant traps - something like Combat with fipronil.

https://www.amazon.com/dp/B002LGY1LA/

Bull crud on ant trap/bait. Your just feeding the ants.
A handfull of dry, regular corn meal, Sprinkled around, will do it.
Ants eat the corn meal. They can't digest it. AND DIE. ###
😎😎😎

Corn meal not really a good idea in a closed terrarium.

Since we are tossing suggestions I have some:

Someone told me that if you sprinkle a single packet of Splenda - the one in the yellow packet - the ants will eat it, they will think it tastes terrible and they will move out. I have tried this outside on South Georgia and mounds and it does work. Later, after the ants vacate, you can scoop out the portion of the soil containing the Splenda.

If the ants come and go, travel outside the terrarium and come back, you could get some Contact paper, remove the paper backing, place it sticky side up on the counter or table, and set the terrarium on the Contact paper. Of course, you don't want the paper to stick to the glass so leave a circle of the backing paper in the center.

You could make a paste of borax (not boric acid), sugar and water and place a little dab in the terrarium. You can put the dab of the bait in something small like a bottle cap so it won't come in contact with your plants.

The quickest way to get ants to leave my potted plants is to drown them out.... I place the pot in a tub of water....
If there's a way for the terrarium to drain, would be the lowest tech solution.

Good one @greene
Thanks I learned something today 😎😎😎!!!

Other than drowning (a fantastic solution for containers with holes in the bottom), the only way I have managed to control the ants here is using bait (Amdro). Maybe make your own tray/trap so it doesn't spill everywhere, or target their entry/exit if there's traffic.

I was about to suggest an ant trap or borox, but considering the comment from Stone to be outstanding. They can't handle water. And a some dish soap added would finish them. The plants will survive an hour in mildly soapy water. The ants won't.

Yeh, it will take some some water-changes to get the soap after (don't overdo it). A baster will help get the last of the water out .

Yeah, its a pain, but you don't want ants.

I like @greene. Ideal better !!!
😎😎😎

Not sure, thought I read that ants hate lavender. Any one else heard this?
If so, take your terr. outside to what ever type of shelter it needs(cool,deep shade,etc) place some lavender twig sprigs inside the container, replace the lid loosely so they can get out/leave. Keep an eye on how the plants are, will they need H2O misted, your nice jar looks quite humid. Don`t know how long the processs will take, two hours or so. Lavender oil on a cotton ball placed inside semi closed jar?
Maybe cedar shavings wrapped in cloth so they don`t spill all over.
Take the terr. OUTSIDE. Don`t try these experiments in your dwelling.
If this doesn`t work maybe I`ll tell you the one `bout the cookie and the vacume cleaner! Ant removal and fun at the same time

This is a 3 gallon self contained terrarium. You do NOT want to be putting anything in it that cannot be completely removed easily.