Crematogaster schimmeri

Crematogaster schimmeri

Crematogaster schimmeri is a small ant species native to Taiwan and Hainan, China. Workers measure around 2.19mm and are yellow in color with a distinctly sculptured head and squared petiole with angulate corners ^[1]. This species belongs to the subgenus Orthocrema and is notable for having a unique soldier caste, intermediate-sized individuals that are morphologically between workers and queens ^[2]. Colonies are monogynous (single queen) with 314-626 workers and 14-23 soldiers ^[2]. They nest in broad-leaved forests and foragers remain active year-round ^[2].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Taiwan and Hainan, China. Nests occur in broad-leaved forests ^[2].
• Colony Type: Monogynous (single queen) colonies with a distinct soldier caste. The soldier caste (called 'intermediates') is a mosaic of queen-like and worker-like traits, they have more eyes than workers but fewer than queens, and lack a spermatheca so cannot reproduce sexually ^[2].
  • Colony: Monogyne
• Size & Growth:
  • Queen: 5.96mm total length ^[2]
  • Worker: 2.19mm total length ^[2]
  • Colony: 314-626 workers plus 14-23 soldiers per colony ^[2]
  • Growth: Moderate
  • Development: Unknown, no direct development data available for this species (Development timeline has not been studied. Based on related Crematogaster species, expect 4-8 weeks at warm temperatures.)
• Antkeeping:
  • Temperature: Keep at 22-26°C. They are a tropical/subtropical species from Taiwan and Hainan, so they prefer warm conditions. A gentle gradient is recommended.
  • Humidity: Moderate to high. Broad-leaved forest habitat suggests they prefer damp conditions. Keep nest substrate moist but not waterlogged.
  • Diapause: No, foragers remain active throughout the year in their natural habitat ^[2]. They do not require hibernation.
  • Nesting: In nature they nest in broad-leaved forests. For captivity, a Y-tong or plaster nest works well. They prefer enclosed nests with some moisture retention. Avoid completely dry setups.
• Behavior: These ants are generally calm but can be defensive when threatened. They have a distinctive habit of raising their gaster when disturbed, this is common in Crematogaster species. Workers are small (2.19mm) so escape prevention should be good, though not as critical as with tiny 1-2mm species. The soldier caste is present in colonies year-round and serves a specialized trophic function, they lay unfertilized eggs that are eaten by larvae ^[2].
• Common Issues: small colony size means slower population growth, patience is required, lack of development data means you may need to experiment with temperatures, soldier caste presence may confuse new keepers, they are normal, not a sign of colony stress, wild-caught colonies from Taiwan/Hainan may have different care requirements than captive-bred

The Soldier Caste

Crematogaster schimmeri has a unique feature among ants, a third caste called 'intermediates' that sits between workers and queens in size and morphology ^[2]. These soldiers are 4.47mm long (compared to workers at 2.19mm and queens at 5.96mm) ^[2]. They have more compound eye ommatidia than workers (101-128 vs 45-59) but fewer than queens (197-225), and they lack ocelli that queens have ^[2]. Most interestingly, soldiers have 12-16 ovarioles (egg-producing tubes) compared to workers who only have 2,but they lack a spermatheca (sperm storage organ) so cannot actually reproduce sexually ^[2]. Instead, soldiers specialize in laying unfertilized eggs that are eaten by larvae, this is their 'trophic' function ^[2]. Soldiers are present in colonies year-round, with 14-23 per colony ^[2]. This is completely normal and not a sign of colony problems.

Housing and Nest Setup

These ants do well in standard ant keeping setups. A Y-tong (acrylic) nest or plaster nest works well, both provide the enclosed, slightly humid environment they prefer. Since workers are only 2.19mm, ensure your escape prevention is decent, though they are not as tiny as some other species. Provide a water tube for drinking and keep the nest substrate moist. A small outworld for foraging allows you to observe their behavior. Because they come from broad-leaved forests in Taiwan and Hainan, they appreciate some cover and darkness in their nest area. ^[2]

Feeding

Crematogaster species are generalist omnivores. They will accept sugar sources (honey, sugar water) and protein (small insects, mealworms, fruit flies). In their natural habitat, foragers are active year-round, so they need regular feeding. Offer a drop of sugar water every few days and protein once or twice a week. Remove uneaten protein after 24 hours to prevent mold. The presence of the soldier caste with their trophic egg-laying may mean the colony has additional nutrition sources, the unfertilized eggs provide protein to developing larvae. ^[2]

Temperature and Seasonal Care

As a species from Taiwan and Hainan (subtropical/tropical), C. schimmeri prefers warm conditions. Keep the nest at 22-26°C. You can use a heating cable on one side of the nest to create a gentle gradient if your room is cooler. Unlike temperate species, they do not require hibernation, foragers remain active throughout the year in their natural habitat ^[2]. This makes them a good choice if you don't want to deal with diapause cycles. However, avoid overheating, temperatures above 30°C can be harmful.

Colony Structure and Growth

Mature colonies have 314-626 workers plus 14-23 soldiers ^[2]. The colony is monogynous, one queen does all the egg-laying ^[2]. The queen is 5.96mm and has 12-20 ovarioles ^[2]. Growth is moderate, you won't see the explosive growth of some fast-growing species, but steady progress. The unique soldier caste means the colony has more complexity than simple worker-only species. Don't be alarmed if you see larger intermediates moving around, these are the soldiers, not new queens. They cannot found their own colonies.

Frequently Asked Questions

References