Solenopsis molesta

North American Thief Ant

🐜 At a glance

Origin: 🌎 North America
Keeping level: Advanced — tiny, clever escape artists. Small sting
Queen: 4–5mm
Workers: 1.5–3mm, golden — tiny
Founding: Fully claustral — but we recommend a drop of protein jelly once a week
Colony form: Many queens (polygyne); up to 100,000 workers in the wild
Nest temperature: Above 26°C by day, 21–24°C at night
Nest humidity: 60–70% in the nest; outworld around 50% at 21–26°C
Workers before moving into a nest: 10+
Winter: No hibernation — keep warm all year

📖 About this species

The North American cousin of our European thief ant, Solenopsis fugax. Tiny, golden and very well organised, thief ants slip into the nests of other ants, steal their food and even carry off their young. Fast-growing escape artists — an escape barrier is a must.

📦 When your ants arrive

⚠️ MOST IMPORTANT: leave the parcel completely unopened, exactly as it arrived, at room temperature for 5 hours. The ants must adjust to your home’s temperature gradually — abrupt temperature changes make ants seriously unwell.
After the 5 hours, check the queen is safe and sound, then leave the colony in its original packaging (test tube still in its tin foil and wrapping) in a quiet spot — in daylight, never direct sunlight — away from vibration and daily household activity.
😴 Give the colony 4 to 5 days of complete rest. The ants were fed before dispatch and need nothing from you during this time. Assemble and water the nest while you wait.
Still workers or a motionless queen after delivery are almost always delivery stress. Check the antennae: moving antennae means she is fine. Almost all recover within 4 to 5 days (a little longer for bigger queens).
Do not remove the black divider inside the test tube (between the two cotton stoppers) — it keeps the ants safe in transit. It has a hole, and the queen and all workers pass through it without any issue.
👑 A queen on her own: keep her test tube wrapped in its tin foil, undisturbed, and feed her once a week — a tiny drop of protein jelly, about half a grain of rice, on a small flat piece of tin foil placed inside the tube next to the dry cotton stopper. In our experience a fed queen is stronger and her brood develops about 30% faster.

🏠 Moving into the ant farm

Keep the colony in its test tube until it has at least 10 workers. Moved earlier, the workers often abandon the queen in the larger space, which can lead to colony failure. A queen bought on her own, with no workers yet, needs a little longer: she stays in her test tube until she has 15+ workers.
Connect the test tube to the nest with the delivery tin foil still on and leave it for 14 days. Then slide the foil back about 1mm every day until the tube is fully exposed to daylight.
If the ants have not moved in 2 days after the tube is fully exposed, wrap the foil back on, wait another fortnight and repeat the whole process — patience is the key. Moving in happens on the ants’ own time: anywhere from a couple of days to 6 months.
The red filter and black cover stay on the nest at all times — it is pitch dark inside. The black cover can come off once a day for 2 to 3 minutes (ideally at night); the red filter once a week for 2 to 3 minutes.
☀️ Place the ant farm in normal daylight, never direct sunlight (the sun can overheat a nest within minutes). Avoid windows, radiators and heaters, vibrating surfaces, speakers and TVs, strong smells such as the kitchen, and busy walkways. Keep a steady room temperature.

🍯 Feeding

🔬 Small ants need small portions: a drop the size of half a grain of rice is plenty for a young colony.
🍯 Sugars for worker energy: our organic ant honey (lab-tested at 81% carbohydrate) or Best Ants UK Ant Nectar (90% dextrose, an even richer energy source) — never sugar water or home-made mixes.
🥩 Protein for the queen and brood: Best Ants UK Protein Jelly or NextSwarm Cricket Mash. Keep protein jelly in the fridge at all times once opened. They love protein and grow fast when it is plentiful.
Feed twice a week, small amounts, in the outworld only. Remove leftovers after 2 days to prevent mould.
🦗 Live food (mealworms, crickets, locusts) is only for established colonies, never small ones. All bought live food carries tiny mites that can destroy a colony, so always scald it first: hold it with tweezers in just-boiled water (no longer bubbling) for 10 to 15 seconds, then chop it in half and serve on a small tin foil tray.

💧 Watering the nest

💧 Use distilled or purified water only — never tap, rainwater or bottled mineral water, even boiled. They carry minerals and microbes that turn a nest green with mould. A litre of distilled water costs a few pounds and lasts over a year.
Water the nest with the pipette provided: pour slowly, a few drops at a time, through the watering hole, and stop as soon as 1 or 2 drops appear inside the nest — that is how you know it is done correctly. More than that is too much.
Once a week is usually right — slightly more in summer, less in winter. Never water the outworld.

🌡️ Temperature and winter

🌴 No hibernation. Solenopsis molesta comes from a warm climate and must stay above 26°C all year round — in a UK home this means gentle heating in the cooler months.
Use the Advanced Heating System Small 4W warming no more than a quarter of the nest, on the side opposite the water inlet, so the ants can choose their temperature. For a colony still in its test tube, use the Heating Mat with Thermostat Small 4W and heat only about 25mm of the tube, at the end opposite the water — never lay the whole tube on the mat.
Never let the colony get cold, and never expose it to abrupt temperature changes.

🤩 Did you know?

Its name comes from the Latin “molestus”, meaning troublesome — it raids kitchens as happily as other ants' nests.
Workers are so small that they can follow tunnels too narrow for the ants they steal from.

⭐ Golden rules | Never break these

🚫 Never put ants in a fridge, and never expose them to abrupt temperature changes. Cold does not kill a colony instantly — the ants get sick and die over the following days — and prolonged cold near freezing damages the sperm a queen stores from her nuptial flight, so she may never lay fertile eggs again.
🚫 Never use gel ant farms, Ytong or concrete nests, or DIY nests.
🚫 Never use tap, rain or mineral water, even boiled.
🚫 Never move a colony into a nest too early, and never tip or shake ants out of their tube.
🚫 Never disturb the colony with tapping or handling — vibration stresses the queen and she can stop laying or eat her eggs.
☀️ Never keep the farm in the dark: ants need daylight for their circadian rhythm. Daylight yes — direct sunlight never.
🧱 Escape artists: keep a fresh PTFE band around the top inner edge of the outworld lid at all times, and never leave the lid open.
🚫 Never release this species into the wild — a colony raised in an ant farm would not survive. If you can no longer keep it, visit our ants adoption page and ask us whether we can adopt it.

🛒 Recommended for this species

📚 These care notes cover the essentials only. Please read the full ant farm setup guide and our thief ant article from A to Z. Questions? Message us through our contact form and we will be happy to help. 💚

Written and reviewed by the Best Ants UK team, keeping ants since 1997.