Springtails were thriving for two months, visible in hundreds every time I lifted a leaf or the cork bark. I added a starter culture of isopods four weeks ago and now I barely see a springtail anywhere. The isopods look fine and I can find them under the wood. Nothing else changed except that I have been running the heat lamp a little longer since the weather turned. Did the isopods outcompete them?
Two other things worth checking:
Leaf litter depth. Springtails need a damp layer of decaying material to live in, and if yours has broken down over two months and not been topped up, their habitat has quietly disappeared. I keep at least two inches of magnolia or oak leaves and add a handful monthly.
Which isopods you added. Powder oranges and dwarf whites are gentle and happy in the same damp conditions. Some of the larger species prefer drier setups, and keepers adjust the tank to suit them, which is what actually harms the springtails. If you changed your misting routine for the isopods, that is your culprit rather than the animals themselves.
Leaf litter is a consumable and people treat it as decoration. I top mine up every month or two, and springtail numbers track that more closely than anything else I do to the tank.
There is a normal population cycle too. Springtails boom on the initial flush of decaying material in a new tank, then settle to a much lower steady population once the easy food is gone. Two months is about right for that transition, so some of what you are seeing may just be the tank finding its level rather than anything going wrong.
Keep a backup culture in a tub on a shelf regardless. A takeaway container with charcoal or coco fibre, a bit of rice or yeast every couple of weeks, and you always have a reseeding source. It takes ten minutes to set up and removes this entire category of worry.
Also check where the water goes when you mist. If the front glass gets the spray and the back corner has been dry for weeks, the population concentrates somewhere you never look. Mine live almost entirely under one piece of wood at the damp end and the rest of the tank looks empty.
@sashiko_sam · 8mo ago · 3 replies
Almost certainly not the isopods. They occupy different niches and coexist in every established tank I have kept, and they are not predators.
The detail in your post that matters is the heat lamp running longer. Springtails are extremely sensitive to the substrate drying at the surface, and a lamp on for more hours dries the top layer even if your hygrometer still reads fine. They do not die so much as move down and out of sight, which looks identical to a crash.
Test it before you buy replacements. Lay a piece of cork flat on the substrate in the dampest corner and put a slice of mushroom or cucumber under it. Come back in 48 hours and lift it. If they are there, your population is fine and you have a moisture and visibility problem, not a population problem.
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@wind_down_wren · 8mo ago
This happened to me almost word for word when I added a second bulb in autumn. I was convinced my isopods were eating them. Deepened the leaf litter and pulled the lamp back an hour and they were everywhere again in about three weeks.
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@flaxseed_fran · 8mo ago
The mushroom slice test is the single most useful diagnostic in this hobby. Cheap, fast, and it answers the question you cannot answer by staring at the glass at 9pm.
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