Springtails in plant soil

So treat the finding as information about your watering. Dry the top layer out between waterings and the population falls on its own, without anything sprayed on the plant.

Constant surface damp is the whole story. Watering little and often keeps the top layer permanently wet, and that layer is where springtails feed and lay eggs.

Rich, organic mixes give them more to eat. Fresh potting mix with a lot of bark, coir or compost often arrives with a small population already in it, which then multiplies or dies back depending on how you water.

Debris on the surface feeds them directly. Fallen leaves, spent flowers, a mulch of coffee grounds or a decorative moss layer all hold water and rot slowly.

Terrariums and closed propagation boxes are their ideal home, and there they are often introduced deliberately because they clean up mold and droppings.

Not in a normal pot. Springtails feed on decomposing material and fungi and are part of what breaks organic matter down into something roots can use.

In very high numbers in seed trays they occasionally graze on the softest tissue of a germinating seedling that is already struggling in soggy mix. Even there the wet mix is the problem and the springtails are the symptom.

They do not bite people, do not carry disease into the home and do not damage the house. Finding them indoors says the mix is wet rather than that the plant has an infestation.

If leaves are yellowing, wilting or spotting, look for the cause elsewhere. A pot wet enough for springtails is usually wet enough for root problems, and that is what to check next.

Fungus gnats are the common confusion. Those are dark flying insects that rise off the surface and drift around the room, and their larvae are thin translucent maggots with a black head that do feed on fine roots.

Root aphids are pale, slow and stay clustered on the roots and the inner pot wall, often with a white waxy dust. They do not jump and they do damage the plant.

Soil mites move as slow pale dots and never spring. They are harmless in the same way springtails are.

Fine white threads that form a web through the mix are fungal growth rather than an animal. That has its own cause, again a surface that never dries.

• Springtails: jump when disturbed, harmless, follow wet mix
• Fungus gnats: fly, larvae eat fine roots, same wet cause
• Root aphids: cluster on roots with white wax, do damage
• Soil mites: slow pale dots, harmless

Let the top inch or two of mix dry out before you water again, and check with a finger rather than by looking. Springtails need continuous damp at the surface, and a dry layer breaks the cycle within a couple of weeks.

Water thoroughly when you do water, until it runs out of the drainage hole, then pour the saucer off half an hour later. Thorough and less often beats a splash every day for the plant as well.

Clear the surface. Take off fallen leaves, spent flowers and any decorative moss, and scrape away the top half inch if it is matted and sour.

A thin layer of coarse sand, grit or fine gravel on the surface dries fast and gives them nowhere to live. It also makes it obvious the next time the mix is staying wet.

For a pot that is badly overrun and permanently wet, repot into fresh, well-draining mix and rinse the old mix off the roots. Check while you are there whether the pot drains at all.

Insecticide sprays on the leaves reach nothing. The animals live in the mix, they are not feeding on the plant, and the spray leaves residue on foliage for no benefit.

Drenching the mix with dish soap solution, hydrogen peroxide or cinnamon does not deal with the cause and can damage roots. As soon as the mix is wet again the population returns.

Letting a plant wilt hard to dry the pot out costs you more than the springtails do. Dry the surface, not the whole root ball, unless the species wants that anyway.

In a closed terrarium, leave them where they are. They are doing the cleanup that keeps the glass from turning moldy.