Setting up a test tube for a founding queen

Dean Hart · 16 September 2026 · updated 21 September 2026

For a fully claustral queen such as Lasius niger, put clean water in the closed end of a test tube and hold it behind a firm cotton plug. Leave a dry chamber for the queen, then close the entrance with breathable cotton. Check for leaks before adding her and keep the tube covered, level and away from direct sun.

A test tube lets you see whether the water is running low without opening the queen's nest. The cotton between her and the reservoir gives her access to moisture while keeping her out of open water. Researchers use variations of this setup for founding Lasius niger colonies, including water supplied through moist cotton.

First, identify the queen well enough to know her founding strategy. This guide describes a closed chamber for a fully claustral founder, such as Lasius niger. Semi-claustral queens need access to food during founding. Socially parasitic queens need a host colony; a better tube won't solve that. The founding-strategy guide explains the difference.

Assemble it before adding the queen

You'll need a clean, undamaged tube, plain cotton wool, clean water and a blunt tool to push the cotton into place. Have a second tube ready so a leaking first attempt doesn't leave you improvising with the queen inside.

Add water to roughly a third to a half of the tube. Leave enough space beyond the reservoir for the queen to turn around comfortably. The 2025 Lasius niger colony study used a third; Szabó and colleagues' founding experiment used a half. There is no single correct fill line.
Push a firm cotton plug down to the water. It should meet the glass all the way around, with its wet face accessible from the chamber. Stop if water squeezes past it.
Lay the empty setup on its side and watch for leaks. The queen's chamber should have no puddle. If water runs into it, empty the tube and repack the cotton before trying again.
Let the queen walk into the dry chamber. Close the entrance with a separate dry cotton plug that fits snugly against the glass. Use cotton for this closure rather than an airtight cap.
Secure the tube so it cannot roll, then cover the chamber with a removable paper or foil sleeve. Keep the entrance unobstructed and the whole setup out of direct sunlight. Label it with the collection date, locality and identification, including any uncertainty.

The wet cotton and the entrance cotton have different jobs. Don't push the entrance plug so far in that the queen is trapped against the reservoir.

Quiet doesn't mean forgotten

Keep the tube somewhere you can inspect it without repeatedly picking it up. Look for remaining water, an intact entrance plug and any water entering the chamber. A cover you can slide back is useful here. Darkness is part of published founding protocols, but it isn't a reason to leave a drying tube unchecked for weeks.

Before adding heat, check the recommended temperature range and winter-rest requirements for the identified species. A temperature used in one laboratory experiment is not a setting for every queen caught in September. Avoid putting the whole tube on an uncontrolled heater.

Fully claustral queens can raise their first workers on stored reserves. They can also eat during founding. Szabó and colleagues found that weekly cricket feeding increased the combined number of pupae and workers in Lasius niger. They also describe practical feeding hazards, including sticky liquid and food waste, and removed leftovers the following day. Keep food separate from the drinking-water reservoir so you can remove leftovers without dismantling the nest. Read the experiment.

When the setup needs changing

Prepare a replacement before the reservoir dries out. If the old tube is still safe, offer the fresh, covered tube through a secure connection or within an escape-resistant container, with ventilation maintained. Give the ants time to move. Don't use shaking, flooding or strong heat to force them out.

A leak into the chamber needs prompt attention. So does contamination spreading through the space the queen and brood occupy. A stain alone doesn't identify what is growing or how dangerous it is; inspect the condition of the chamber rather than diagnosing it from colour.

Once workers arrive, connect the tube to a small, ventilated, escape-resistant container where you can place food and remove leftovers. The tube can remain their nest while its water supply and living chamber are in good condition. There is no need to buy a large formicarium because the first worker has appeared. If you're still choosing what to keep, start with the species' needs.

Frequently asked questions

How much water goes in a queen ant's test tube?

About a third to a half is a practical starting point, leaving room for a cotton barrier and a dry chamber where the queen can turn around. The reservoir must stay behind the cotton when the tube is laid on its side. Test that before adding the queen.

Does a queen ant need food in the test tube?

That depends on her species. A fully claustral queen can raise first workers on body reserves; semi-claustral queens need food during founding. Fully claustral does not mean unable to eat: experiments with Lasius niger found benefits from supplemental cricket feeding.

When should I replace the tube?

Prepare a fresh tube if the water supply is running out, the reservoir leaks or contamination is spreading into the living chamber. A worker count or a fixed number of weeks is not a replacement rule.

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