Pavement Ant

Tetramorium immigrans (formerly classified under T. caespitum in North America) is the ubiquitous pavement ant found nesting under sidewalks, driveways, and building foundations across the eastern United States and southern Canada. These small but tough ants are excellent for beginners — they are fully claustral, tolerate a wide range of conditions, grow at a moderate pace, and accept nearly any food offered. Their territorial sidewalk battles in early summer are a familiar sight in suburban neighborhoods.

### Founding Method

T. immigrans queens are fully claustral and require no feeding during the founding stage. A single queen sealed in a test tube setup will produce her first workers in approximately 6–8 weeks at 24 °C. Interestingly, this species can sometimes be polygynous — multiple queens coexisting peacefully in a single colony. If you catch several queens from the same flight, you can attempt pleometrotic founding (housing 2–3 queens together), and they will often cooperate through the founding stage. In some cases, the colony remains polygynous permanently, though workers may cull down to a single queen over time.

### Growth Timeline

Growth is moderate and steady:

• **Year 1:** 30–50 workers with a single queen. Polygynous colonies grow faster.
• **Year 2:** 200–600 workers.
• **Year 3:** 1,000–3,000 workers.

### Mature Size

Mature wild colonies contain 10,000–20,000 workers. Multi-queen colonies can grow even larger. In captivity, colonies of several thousand workers are achievable within 3–4 years with consistent care.

### Test Tube Setup

Use a standard 12 mm or 16 mm test tube with a water reservoir. Tetramorium workers are very small (2.5–4 mm), so pack the cotton plug tightly — even tiny gaps will allow them to escape. A rubber stopper with a drilled hole plugged with fine mesh is even more secure. Keep the tube in darkness at 22–26 °C.

### Formicarium

Once the colony reaches 30–50 workers, transition to a formicarium. Good options for this small species include:

• **Ytong nests:** Carve narrow tunnels (2 mm wide) and small chambers (3–4 mm tall). The porous material provides excellent humidity regulation.
• **Plaster nests:** Inexpensive and easy to make. Pour dental plaster into a container, use clay or sculpting tools to form chambers and tunnels before it sets.
• **Acrylic sandwich nests:** Great visibility. Choose a "small species" model with appropriately sized tunnels.
• **3D-printed nests:** Increasingly popular, with designs specifically for small species available from community sellers.

Avoid nests designed for large species like Camponotus — oversized chambers stress small ants and make it difficult for workers to tend brood effectively.

### Outworld

A small plastic container (takeaway container or lab dish) with fluon or PTFE barriers works well. Because Tetramorium workers are tiny, apply barriers carefully and check for any microscopic gaps. Baby powder mixed with rubbing alcohol is an additional barrier option. Provide a water source and feeding stations.

### Protein

T. immigrans has a broad diet and readily accepts most protein sources:

• **Insects:** Fruit flies, pinhead crickets, small mealworm pieces, springtails. Cut larger prey items into manageable pieces for small colonies.
• **Hard-boiled egg yolk:** Extremely well-accepted. A tiny crumb provides ample protein for a small colony.
• **Freeze-dried bloodworms:** Available at pet stores. Rehydrate a small piece before offering.

### Sugar

Offer sugar water (1:4 ratio) or diluted honey as a constant energy source. Tetramorium workers are not as sugar-fixated as Lasius but still need regular carbohydrate supplementation.

### Seeds

Uniquely among common beginner species, T. immigrans is partially granivorous — workers collect and consume small seeds. Offer:

• Chia seeds
• Poppy seeds
• Finely crushed birdseed
• Quinoa (raw)

Seeds provide a slow-release food source and are especially useful as supplemental feeding during vacations. Scatter a few seeds in the outworld and the ants will carry them into the nest to process.

### Grease & Fats

Pavement ants are sometimes called "grease ants" because they are attracted to fatty foods. A tiny drop of olive oil, a sliver of nut butter, or a small piece of cooked (unseasoned) meat is eagerly collected. Do not overdo fatty foods — they turn rancid quickly.

### Frequency

• **Under 50 workers:** Sugar always available, protein every 3–4 days, a few seeds scattered in outworld.
• **50–500 workers:** Sugar always available, protein every 2 days, seeds refreshed weekly.
• **500+ workers:** Sugar always available, daily protein, seeds and grains ad libitum.

### Water

Keep a fresh water source in the outworld at all times. A cotton-plugged test tube water tower prevents drowning and provides steady hydration.

### Optimal Ranges

• **Active season:** 22–26 °C (72–79 °F). Slightly warmer than *Lasius niger* for optimal brood development.
• **Nest humidity:** 50–60%. Not especially moisture-demanding.

### Heating

At typical room temperature (21–23 °C), no supplemental heating is needed. A small heat mat under one end of the nest can boost development speed by 1–2 °C if your home runs cool. Always create a gradient — never heat the entire nest uniformly.

### Humidity Management

Hydrate Ytong or plaster nests every 5–7 days through a reservoir or syringe. The nest should have a visible moisture gradient: one side slightly damp, the other dry. T. immigrans is tolerant of moderate dryness but brood development slows in very dry conditions.

### Required?

Yes — hibernation is required. As a temperate species originally from Europe and now established across cooler North American climates, T. immigrans needs a cold dormancy period for long-term queen health and colony vigor.

### Duration

4–5 months, November through March. A minimum of 10–12 weeks of cold is recommended. This species naturally experiences extended winters in its range and tolerates longer hibernation periods without issue.

### Temperature Range

5–10 °C (41–50 °F). These ants are cold-hardy and can survive brief dips to near freezing, but sustained temperatures below 3 °C should be avoided in captivity.

### Preparation

1. In October, gradually reduce temperature by moving the colony to a cooler room (15–18 °C) for 1–2 weeks.
2. Offer a generous feeding of protein and sugar before the final cooldown.
3. Ensure all water reservoirs are topped off.
4. Remove or disconnect the outworld to prevent wandering during dormancy.
5. Move to the hibernation location (wine cooler, garage, unheated room).

### Waking

In March, reverse the process over 1–2 weeks. Move from cold storage to a cool room (15 °C) for a week, then to room temperature. Provide sugar water immediately and protein within a day. Brood production resumes within 1–3 weeks.

### Season & Conditions

Nuptial flights occur primarily in June and July in the northeastern United States, sometimes extending into early August in cooler regions. Flights launch on warm, humid afternoons and evenings, usually at temperatures above 24 °C. They are smaller in scale than Lasius niger flights but still produce large numbers of queens.

### Catching Queens

After mating, look for wingless queens on:

• Sidewalks and pavement (their preferred nesting habitat)
• Building foundations and walls
• Under rocks and paving stones — turn over flat stones near known colonies to find freshly mated queens that have already begun founding

Queens are 7–8 mm long, stocky, and dark brown to black with faint ridges on the head and thorax (visible under magnification). They are notably larger than workers (2.5–4 mm) and move slower.

### Post-Flight Tips

• House queens individually or in groups of 2–3 to attempt polygynous founding. Multi-queen colonies often grow faster in the first year.
• Set up test tube water reservoirs and store in darkness.
• Eggs appear within 1–2 weeks; first workers in 6–8 weeks.
• If attempting pleometrosis, monitor for aggression once workers arrive. Separate queens immediately if fighting occurs.

### Escapes

The number one problem with Tetramorium in captivity. These ants are extremely small and can escape through gaps that seem impossibly narrow. Prevention is critical:

• Pack cotton plugs as tightly as possible.
• Apply fluon in a wide band (3+ cm) and reapply every 3 weeks.
• Seal all tubing connections with petroleum jelly or plumber's tape.
• Check for condensation trails on outworld walls — ants can walk through water droplets that bridge fluon barriers.

### Mites

Grain mites are common with this species because of their diverse diet — seed and protein remnants attract mites quickly. Remove all uneaten food within 12–24 hours. If mites establish, transfer the colony to a clean nest.

### Slow Founding

Some queens take longer than expected to produce nanitics, especially if caught late in the season and hibernated before founding completes. This is normal. As long as the queen has eggs or larvae, she is healthy — be patient.

### Fungal Infections

Occasionally, individual workers develop visible fungal growths (white fuzz on the body). Isolate the affected ant if possible, or the colony will usually remove it themselves. Ensure ventilation is adequate and humidity is not excessive.

1. **Embrace their diet diversity.** Pavement ants are one of few beginner species that eat seeds. Take advantage of this — scatter chia or poppy seeds as a supplemental food source, especially useful during short vacations.

2. Size your nest appropriately. These are small ants. Housing them in a nest designed for large species leads to poor brood care and stressed workers. Choose or build a formicarium with tunnel widths of 2–3 mm.

3. Try multi-queen founding. If you catch several queens, house 2–3 together. T. immigrans is one of the few common species where polygynous founding frequently succeeds, giving you a faster-growing colony.

4. Seal everything twice. Budget extra time for escape-proofing. Double your barriers: fluon on the outworld walls plus petroleum jelly on every tubing joint. These ants will find the one gap you missed.

5. Do not underestimate them. Despite their small size, mature Tetramorium colonies are impressively active and display complex foraging behaviors, including trail recruitment and territorial combat. A well-established colony of several thousand workers is a genuinely spectacular sight.