Myrmecocystus semirufus
Half-Red Honeypot Ant
Photo: Jake Nitta, via iNaturalist, licensed under CC BY 4.0.
🐜 At a glance
Origin: Southern California and northern Baja California; desert mountain slopes, oak and juniper woodland
Nest temperature: 26–29°C; heater set to 28°C under a quarter of the nest
Outworld temperature: 18°C night, up to 28°C day; by day like the nest or a degree or two cooler
Humidity: Nest 50–70%; outworld about 50%, never watered
Winter: No rest in year one; from year two: Nov–end Feb at room temperature, heater off
Move to a nest: 10+ workers; 15–20 is better
Size: Queen about 13–14 mm; workers about 4–8 mm, red head and thorax
Colony: One queen only; hundreds in year one, 1,000+ later
📖 About this species
A bold, sun-loving honeypot ant from the desert mountains of California and Mexico, with a rusty-red head and thorax and a dark gaster. A fast daytime hunter that stores nectar in its repletes.
🍯 Feeding
Proteins: Protein Jelly (keep in the fridge) or Cricket Mash
Carbohydrates: organic Ant Honey or Ant Nectar, far better than sugar water or home-made mixes, offered at every feed: sugars are vital for the repletes
Twice a week, small amounts, outworld only; remove leftovers after 2 days. Live food only for established colonies: scalded, cut in half, never for small colonies.
💧 Watering the nest
Distilled or purified water only. Never tap, rain or bottled mineral water, even boiled (mould and fungus).
Pipette a few drops through the watering hole; stop when 1–2 drops appear inside. About once a week, or when the meter drops below 50%.
Never water the outworld; keep it at about 50% humidity. A watering test tube in the outworld gives a safe drink.
🏠 Setting up the ant farm
A7 Plus ant farm kit (built-in digital meter); A6 with Meter once the colony is big
Advanced Heating System Small 4W under one quarter of the nest, opposite the watering area, set to 28°C (a must in UK homes)
Daylight, never direct sunlight; away from windows, radiators, vibrations, speakers and kitchens
Escape risk: high. PTFE Fluon band on the top inner edge of the outworld lid, reapplied every 2–4 weeks
💡 Good to know
North American ant: not sold by Best Ants UK, may be illegal or impossible to import to the UK, and we don't encourage importing ants
Active by day; a keen hunter and scavenger of small insects
Brood takes about 7–9 weeks from egg to worker; fast, active workers, so PTFE is a must. Never release: not a UK ant. Can't keep it? See our ant adoption page
⭐ Golden rules | Never break these
🚫 Never put ants in a fridge, shed or garage, and never expose them to abrupt temperature changes.
🚫 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 release ants into the wild. If you can no longer keep a colony, 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 Myrmecocystus semirufus care guide 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.