Pheidole morrisii

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Eastern United States from Long Island, New York to Florida, west to Illinois, Missouri, Oklahoma, and Texas. Prefers pure sandy soils in xeric habitats including pine barrens, old fields, open grasslands, and sandhill ecosystems ^[1][2][6].
• Colony Type: Mostly monogynous, with occasional polygyny in northeastern populations and polydomous colonies in southeastern populations ^[2][5].
• Size & Growth:
  • Queen: Approximately 5-6 mm, inferred from Pheidole genus patterns
  • Worker: Minors: 2.5-2.8 mm, Majors: 3.0-5.0 mm ^[4][3]
  • Colony: Up to 37,400 workers ^[5]
  • Growth: Fast
  • Development: Approximately 4-5 weeks (first minors at ~30 days) ^[2] (Development is temperature-dependent, brood development occurs fastest in warm conditions. Larvae enter diapause overwinter and complete development in spring.)
• Antkeeping:
  • Temperature: Keep nest area around 24-26°C. Brood prefers approximately 25°C ^[5].
  • Humidity: Low, they prefer dry sandy substrates. Provide a water tube but keep the nest area relatively dry ^[2][6].
  • Diapause: Yes, colonies require winter cooling for 3-4 months at 10-15°C ^[5].
  • Nesting: Natural nesting involves deep vertical passages with chambered architecture. In captivity, provide deep soil-based formicarium or Y-tong nest with sand/soil mixture ^[5][2].
• Behavior: Pheidole morrisiii is competitively dominant with aggressive foraging. Minor workers forage singly, often at night, while majors help carry large food items. Workers forage up to 8 meters from the nest ^[2]. They possess functional stings ^[7]. Escape prevention is important due to foraging range.
• Common Issues: colonies can be outcompeted by invasive fire ants in disturbed areas, keep away from other aggressive species, overwintering failure is common if colonies are kept too warm or too wet during dormancy, large colony size means they need significant space, start planning for a large formicarium early, wild-caught colonies may have parasites that can devastate captive colonies, seed collection behavior means they may attempt to store seeds in nest chambers, monitor for mold issues

Nest Preferences and Housing

In the wild, Pheidole morrisiii nests exclusively in the ground, preferring pure sandy soils. They construct elaborate subterranean nests with vertical shafts connecting lobed chambers, typically 0.5-2 meters deep. Colonies often build distinctive crater mounds at the nest entrance, or nest at the base of grass clumps ^[2][5]. For captive care, provide a deep soil-based formicarium with at least 15-20 cm of substrate depth to allow natural tunnel construction. A Y-tong nest also works well if provided with appropriate tunneling media. Test tube setups are suitable for founding colonies but will need upgrading as the colony grows. These ants do best with a dry nest chamber connected to a foraging area with a water tube for humidity.

Feeding and Diet

Pheidole morrisiii is primarily a scavenger but also collects seeds, making them unusual among eastern Pheidole species. In captivity, offer a varied diet including protein sources (small insects like fruit flies, mealworms, crickets) and carbohydrates (sugar water, honey). They readily accept seeds, and major workers possess large mandibles capable of grinding seeds ^[8]. Feed protein 2-3 times per week and provide constant access to sugar water. Remove uneaten food promptly to prevent mold. Their aggressive foraging means they'll readily discover and exploit food sources throughout their foraging area.

Temperature and Seasonal Care

These ants thrive at warm temperatures around 24-26°C in the nest area. Research shows brood is actively moved to the warmest available regions, approximately 25°C is ideal for brood development ^[5]. In summer, ants move brood to upper nest regions to take advantage of surface warmth, while in winter they relocate brood deeper where temperatures remain more stable. During the active season, a small heating cable on one part of the nest creates a beneficial temperature gradient. For overwintering, colonies require a cool period (10-15°C) for 3-4 months. This coincides with natural larval diapause, worker brood enters dormancy over winter and completes development in spring ^[5].

Colony Structure and Caste System

Pheidole morrisiii exhibits extreme worker polymorphism with two distinct castes: minor workers (approximately 88% of workforce) and major workers/soldiers (approximately 12%). Minor workers are small (2.5-2.8 mm) and handle most day-to-day tasks including foraging. Major workers have dramatically enlarged heads (3.0-5.0 mm) and specialize in defense, seed processing, and heavy food transport ^[9]. Notably, majors actively participate in outside-nest tasks, they emerge from the nest to help carry large food items back to the colony, a behavior less common in other Pheidole species ^[2]. The caste ratio can shift based on environmental conditions, colonies in more competitive environments produce higher proportions of majors. This species also shows geographic variation: northeastern colonies are occasionally polygynous while southeastern colonies are monogynous but often polydomous ^[2][5].

Growth and Development

Colony growth is fast. Under laboratory conditions, first minor workers emerge in approximately 30 days, with first major workers appearing around day 50. A colony can reach several hundred workers within just 8 months ^[2]. Wild colonies reach much larger sizes, research using wax casting found colonies ranging from 800 to nearly 49,000 total ants, with worker counts from 500 to over 37,000 ^[5]. Colonies must reach approximately 3,000 workers before they can produce reproductive alates (winged queens and males). The colony produces worker brood in two distinct seasonal peaks, spring and fall, with larvae produced in fall entering diapause and overwintering before completing development ^[5]. This means winter cooling is essential for proper colony development.

Behavior and Defense

This is a competitively dominant ant species known for aggressive foraging and strong nest defense. Workers forage individually, often at night, and can travel up to 8 meters from the nest to locate food. When food is discovered, major workers emerge to assist with transport back to the colony ^[2]. Their large majors serve as effective defenders against threats, and they compete vigorously with other ant species. Research shows they are ecologically similar to the invasive fire ant (Solenopsis invicta) in worker size, diet, and colony characteristics, this similarity means they are often displaced by fire ants in disturbed habitats ^[10]. They possess functional stings but rarely use them against keepers. Standard escape prevention works well, though their foraging range means they will explore any gaps in their enclosure.

Frequently Asked Questions

Report an Issue

The current care sheet is based fully on literature. See inconsistencies, or something that's incorrect? Please report here, it will be resolved after review from an admin. Contributing to the blogs tab also helps providing information, to make us be able to further improve the caresheets. Thank you for your support!

References