Vollenhovia emeryi

Quick Summary

• Difficulty: Expert
• Origin & Habitat: Native to Japan, Korea, China (Yunnan, Zhejiang), Taiwan, and Thailand ^[9][10]. Found in secondary forests, both montane and lowland riverside forests, where it nests in decaying wood and under the bark of fallen trees ^[1][9]. In the United States, populations are established in riparian and floodplain forests in Washington D.C., Maryland, Virginia, and Pennsylvania ^[8].
• Colony Type: Two colony types exist ^[1]: Type 1 colonies are usually monogynous (single queen) with long‑winged queens, found mainly in mountain forests, Type 2 colonies are usually polygynous (multiple queens) with short‑winged queens, found in or near riverside forests. Both types nest in decaying wood and have been found coexisting in the same area ^[6]. In North America, only the short‑winged polygynous type has been observed until recently ^[9].
• Size & Growth:
  • Queen: Size data unavailable, head width measurements exist but are not body length. Queens are slightly larger than workers, but precise total length is not reported in the literature.
  • Worker: 2.5 mm ^[1][2]
  • Colony: Up to several hundred workers. One wild colony in the US contained only 28 workers and 3 dealate queens ^[8].
  • Growth: Moderate
  • Development: Unknown, development time has not been studied for this species. For related small Myrmicinae, the full cycle from egg to worker may take 6-10 weeks at room temperature, but this is only a rough guess. (Development depends on temperature and nutrition. Colonies with more food produce more new reproductives ^[7].)
• Antkeeping:
  • Temperature: Keep at a stable room temperature, roughly 20-25 °C. No specific optimal temperature is known, avoid extremes. If the colony enters diapause, provide a cool period (10-15 °C) for 2-3 months.
  • Humidity: High humidity is critical. In captivity, colonies show a strong preference for extremely wet nest sites, one colony moved into the gap between a water hose and a plastic container wall ^[8]. Keep the nest substrate consistently damp but not waterlogged. A moisture gradient is helpful.
  • Diapause: Yes. Alate females and males hibernate inside the nests ^[1]. New reproductives emerge in late summer to autumn and mate before winter ^[11]. Provide a winter dormancy period of 2-3 months at around 10-15 °C.
  • Nesting: Use test tubes with water reservoirs, Y‑tong (AAC) blocks, plaster nests, or naturalistic setups with decaying wood. Avoid acrylic nests. The nest should be kept damp and offer tight, humid chambers. Workers will abandon dry areas.
• Behavior: Workers are slow‑moving and non‑aggressive ^[8]. They do not have a painful sting, they use a smearing defense (modified stinger wipes venom onto enemies). When disturbed, workers quickly move eggs and larvae to sheltered spots ^[8]. They are not skilled climbers, but because of their small size (2.5 mm), standard escape prevention (e.g., fluon or mineral oil barriers) is recommended.
• Common Issues: humidity is the most critical factor, colonies will abandon a dry nest and fail if the substrate becomes too dry, this species is invasive in the eastern United States, never release ants outside their native range, the complex reproductive system means that colonies with poor nutrition may produce only short‑winged queens, limiting dispersal ability, wild colonies may contain the parasitic ant Vollenhovia nipponica, watch for smaller companion ants and separate if needed, workers are monomorphic (all same size) and non‑reproductive ^[17], gynandromorphs (individuals with both male and female tissue) occur frequently in some populations, but this does not affect colony health ^[13]

Understanding the Unique Reproductive System

Vollenhovia emeryi has one of the most unusual reproductive systems known in ants. Queens produce new queens through parthenogenesis (asexual reproduction), the daughters are genetically identical clones of their mother ^[7]. Males are produced through androgenesis, they are clones of their fathers, containing only the father’s genetic material while the mother’s genome is eliminated ^[5]. Workers, however, are produced through normal sexual reproduction ^[4]. This creates two completely separate genetic lineages: the queen lineage (clonal) and the male lineage (also clonal), with no gene flow between them ^[12]. This system is called AQS + MC (Asexual Queen Succession plus Male Cloning) ^[13]. The practical implication for keepers is that your colony’s queen will produce more queens like herself, while workers come from sexually produced eggs. Thelytokous parthenogenesis (automixis with central fusion) is the mechanism ^[13]. About 27% of offspring from inbreeding experiments are diploid males (sterile), confirming a two‑locus complementary sex determination system ^[14][11].

Queen Morphs and Colony Types

This species has two distinct queen morphs that determine colony structure. Long‑winged (L) queens have fully developed wings averaging 3.0 mm in length and can fly to disperse and found new colonies ^[6]. Short‑winged (S) queens have reduced wings averaging only 2.0 mm and cannot fly, they mate inside their natal nest before hibernation ^[7]. L‑queen colonies tend to be monogynous (single queen) and are found mainly in mountainous forests. S‑queen colonies tend to be polygynous (multiple queens) and are found in lowland riverside forests ^[1]. The short‑winged morph is evolutionarily derived from the long‑winged morph ^[15]. In the laboratory, colonies fed more food produce both queen types, while poorly‑fed colonies produce only short‑winged queens ^[7]. This means nutrition strongly influences which type of queen develops. Queen polymorphism is also associated with Wolbachia infection, all L‑morph populations are infected, while S‑morph populations may or may not carry Wolbachia ^[15].

Housing and Nest Setup

Vollenhovia emeryi requires moist, humid conditions. In the wild, they nest in decaying wood and fallen branches in forests ^[9]. In captivity, they show a strong preference for extremely wet nesting sites, one study observed colonies moving into the gap between a water hose and plastic container wall ^[8]. Use test tubes with water reservoirs or Y‑tong (AAC) blocks with moisture chambers. Avoid acrylic nests. Provide a naturalistic setup with pieces of rotting wood. The nest material should remain damp but not flooded. Keep the outworld moderately humid as well. These ants are not aggressive and handle disturbance by moving brood to safer locations rather than fleeing ^[8]. Use standard escape prevention, while not particularly good climbers, their small size means they can slip through small gaps. Workers are monomorphic ^[16] and non‑reproductive ^[17].

Feeding and Diet

Vollenhovia emeryi is an omnivore, likely feeding on small insects, honeydew, and nectar in nature. Their small worker size (2.5 mm) means prey items should be appropriately sized. Offer small insects like fruit flies, pinhead crickets, springtails, or other tiny arthropods. Sugar sources such as honey water or sugar water are readily accepted. Feed small amounts regularly and remove uneaten food to prevent mold. In laboratory studies, colonies were fed a standard ant diet ^[11]. The complex reproductive system means well‑nourished colonies produce more reproductive individuals (including long‑winged queens), while poorly‑fed colonies produce fewer ^[7]. There is no evidence that workers require specialized feeding beyond standard ant care.

Seasonal Care and Hibernation

In their native range, alate reproductive females and males hibernate within the nests ^[1]. New reproductives emerge from late summer to autumn ^[11]. Provide a winter dormancy period of 2-3 months at temperatures around 10-15 °C. During this time, reduce feeding and keep the colony slightly cooler but still moist. In spring after hibernation, colonies that produced short‑winged queens will split through budding, the queens and some workers establish new nest locations nearby ^[7]. This is an important part of their natural cycle and should be replicated in captivity for long‑term colony health. Long‑winged queens likely mate after hibernation during nuptial flights ^[7].

Invasive Status and Legal Considerations

Vollenhovia emeryi is an invasive species in the eastern United States, established in Washington D.C., Maryland, Virginia, and Pennsylvania ^[8][18]. The first US population was discovered in 1986 in Rock Creek Park, Washington D.C. ^[9]. It is believed to have been introduced with Japanese cherry trees gifted to the US in 1910-1912 ^[8]. Only short‑winged queens have been found in North America, so long‑distance dispersal is thought to occur via rafting in wood during floods ^[8]. If you live in these areas and collect wild colonies, do not release them outside their native range. Conversely, if you are outside the invasive range and obtain this species, it must be kept in secure enclosures to prevent accidental establishment. Always check local regulations before keeping ant species. This species is not known to displace native ants in US surveys ^[8], but caution is still required.

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