Stenamma exasperatum

Stenamma exasperatum

Stenamma exasperatum is a small, yellowish-brown ant species native to California, belonging to the Myrmicinae subfamily. Workers measure 0.70-0.77mm in head width and 1.00-1.13mm in mesosoma length, making them relatively small ants with a distinctive coarse, reticulate sculpturing on the thorax and gaster ^[1]. The species is closely related to Stenamma heathi, sharing similar clypeal structure and gastric sculpture, but can be distinguished by its more clearly reticulate head and thorax, and fully erect hairs on the scapes and tibiae ^[2]. This species is known only from California, particularly from the Calaveras Big Trees area in Calaveras County, where it was first collected under a stone in a Sequoiadendron grove ^[2]. The species name 'exasperatum' reflects the collector's frustration at discovering it was yet another new species after initially thinking it was S. heathi ^[2].

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Native to California, USA, in the Nearctic biogeographic region ^[3]. Found in cool, shaded habitats including Sequoiadendron groves and pine-fir forests, typically under stones or in leaf litter ^[2]. The latitude of approximately 41.28°N indicates a temperate mountain environment ^[3].
• Colony Type: Colony structure is unconfirmed. Based on related Stenamma species, likely monogyne (single queen) colonies with moderate worker counts.
• Size & Growth:
  • Queen: Undescribed in original literature, estimated 5-7mm based on genus patterns
  • Worker: 0.70-0.77mm head width,1.00-1.13mm mesosoma length ^[2]
  • Colony: Likely under 500 workers based on typical Stenamma colony sizes
  • Growth: Moderate, typical for forest-dwelling Myrmicinae
  • Development: Estimated 6-10 weeks at optimal temperature based on genus patterns (Development time inferred from related Stenamma species, specific data unavailable for this species)
• Antkeeping:
  • Temperature: Keep at 18-22°C, they prefer cool, stable conditions typical of their shaded forest habitat. Avoid overheating. A slight temperature gradient allows ants to regulate their own exposure.
  • Humidity: Moderate to high humidity (50-70%). Their natural habitat under stones and in litter suggests they prefer consistently moist substrate without being waterlogged. Provide a damp nest area with some drier areas for escape.
  • Diapause: Yes, as a Nearctic species from California's mountains, they likely require a winter dormancy period. Provide 2-3 months at 5-10°C during winter.
  • Nesting: Prefers naturalistic setups with soil or plaster that can hold moisture. Y-tong (AAC) nests also work well. They do well with moderate chamber sizes and prefer tight, enclosed spaces. Keep nest substrate consistently moist.
• Behavior: Stenamma are generally calm, non-aggressive ants with slow, deliberate movement patterns. They are not known for stinging, Myrmicinae have functional stingers but Stenamma are not aggressive defenders. Workers forage individually rather than in raiding columns. Their small size means they can escape through tiny gaps, use fine mesh barriers. They are cryptic and spend much time inside the nest.
• Common Issues: escape prevention is critical due to their tiny size, they can squeeze through standard test tube cotton, colonies may fail if kept too warm, they prefer cool conditions, slow growth can frustrate beginners who overfeed or disturb the colony, wild-caught colonies may contain parasites that can devastate captive colonies, they prefer dark, quiet locations, excessive disturbance causes stress

Housing and Nest Setup

Stenamma exasperatum does well in naturalistic setups with moist soil or plaster substrates, which mimic their natural under-stone nesting habitat. Y-tong (AAC) nests also work well for this species. The nest should have chambers scaled appropriately for their small size, avoid large, open spaces. Keep the nest area consistently moist but not waterlogged. Place the setup in a cool, shaded location away from direct sunlight and vibrations. These ants prefer dark conditions and will be more active if the nest is covered or placed in low-light areas. A small outworld for foraging completes the setup. ^[2]

Feeding and Diet

Like other Stenamma species, they likely accept small protein sources such as fruit flies, small mealworms, and other tiny arthropods. They probably also consume honeydew from aphids and sugar water or honey as an energy source. Feed small prey items a few times per week, adjusting based on colony size and consumption. Remove uneaten prey after 24-48 hours to prevent mold. Sugar sources should be offered occasionally but are not their primary diet. Their small size means prey items must be appropriately sized, avoid large crickets or other oversized insects.

Temperature and Seasonal Care

Keep the nest at 18-22°C, this cool temperature range reflects their mountain forest habitat in California. Avoid temperatures above 25°C, as overheating can be fatal. A heating cable on one side of the nest can create a gradient, but ensure part of the nest stays cool. During winter (October-March), provide a diapause period at 5-10°C to simulate their natural seasonal cycle. This rest period is important for colony health and may trigger reproductive behavior in spring. Do not feed during diapause but keep the substrate slightly moist. ^[3]

Behavior and Temperament

Stenamma exasperatum is a calm, non-aggressive species with slow, deliberate movement. Workers are cryptic and spend much time inside the nest, emerging to forage individually rather than in groups. They are not known for stinging and pose no danger to keepers. Their small size means they can escape through remarkably tiny gaps, use fine mesh (at least 0.5mm) on all openings and consider applying Fluon to barrier edges. They do not form large colonies quickly, so patience is required. Avoid disturbing the colony frequently, as they prefer stable, quiet conditions.

Colony Establishment

If you obtain a founding queen, she will likely seal herself in a chamber and raise the first brood claustrally, living off her stored fat reserves until workers emerge. The first workers (nanitics) will be smaller than mature workers. Allow the colony to establish without disturbance, do not check the founding chamber for several weeks. Once workers are present, you can begin offering small prey items. Colony growth will be gradual, with workers living for several years. Multiple queens should not be combined unless pleometrosis is confirmed for this species.

Frequently Asked Questions

References