Lasius sonobei

Lasius sonobei

Lasius sonobei is a small yellow ant native to Japan, belonging to the nearcticus group within the flavus clade. Workers measure 2.5-3.5mm and have a distinctive appearance with scapes that usually exceed 0.95 times the head width, and lack erect hairs on the scapes and tibiae. The species is abundant in southern Japan (Honshu, Shikoku, Kyushu, Yakushima) but becomes rare in the Tohoku district of northern Honshu, with its northernmost limit around Sendai. Nests are constructed in soil and under stones in warm-temperate forest habitats.

Quick Summary

• Difficulty: Medium
• Origin & Habitat: Japan (southern Honshu, Shikoku, Kyushu, Yakushima Island). Nests in soil and under stones in warm-temperate regions ^[1][2].
• Colony Type: Single-queen (monogyne) colonies, standard for the Lasius genus. Queens are likely claustral founders, sealing themselves in to raise the first brood alone.
  • Colony: Monogyne
  • Founding: Claustral
• Size & Growth:
  • Queen: Estimated 7-9mm based on typical Lasius queen size (related species in the flavus clade)
  • Worker: 2.5-3.5mm ^[1]
  • Colony: Estimated several hundred workers based on related Lasius species
  • Growth: Moderate, typical for Lasius genus
  • Development: Estimated 6-8 weeks at optimal temperature based on related Lasius species (Development time follows typical Lasius patterns, warmer temperatures within range accelerate development)
• Antkeeping:
  • Temperature: Keep around 20-24°C. As a warm-temperate species from southern Japan, they prefer moderate warmth without extreme heat.
  • Humidity: Maintain moderate humidity. Nest in soil and under stones suggests they prefer damp but not waterlogged substrate. Keep the nest substrate moist but allow some drying between waterings.
  • Diapause: Yes, as a temperate species from Japan, they require a winter rest period. Reduce temperature to around 10-15°C for 2-3 months during winter.
  • Nesting: Soil nests and under-stone nesting in the wild. In captivity, standard test tubes, Y-tong nests, or plaster nests work well. Provide a moisture gradient so ants can choose their preferred humidity zone.
• Behavior: Docile and non-aggressive typical of Lasius ants. Workers are small and yellow, making escape prevention important despite their calm nature. They forage for honeydew and small insects. Like other Lasius, they may tend aphids for honeydew. Escape risk is moderate, their small size means gaps in housing should be sealed properly.
• Common Issues: colonies may fail if hibernation is not provided, this temperate species needs winter rest, small workers can escape through tiny gaps, use proper escape prevention, slow founding phase can worry beginners, claustral queens seal in and don't emerge until workers hatch, overfeeding can cause mold in nest setups, remove uneaten food promptly, humidity that is too high or too low can cause colony stress

Housing and Nest Setup

Lasius sonobei nests naturally in soil and under stones in Japan's warm-temperate forests. In captivity, they adapt well to various nest types. Test tube setups work excellently for founding colonies, the queen seals herself in one tube while workers eventually occupy both. Y-tong (acrylic) nests and plaster nests are also suitable once the colony grows. Provide a water tube attached to the nest for humidity. Because they nest in soil in the wild, a thin layer of substrate in a naturalistic setup helps them feel at home. Ensure the nest has chambers scaled to their small 2.5-3.5mm worker size. ^[1]

Feeding and Diet

Like other Lasius species, Lasius sonobei is omnivorous with a preference for sugar sources. They naturally tend aphids and collect honeydew, so sugar water (1:3 ratio with water) or honey water makes an excellent constant food source. For protein, offer small insects like fruit flies, small mealworms, or cricket pieces. Feed protein 2-3 times per week, and keep sugar water available at all times. Remove uneaten prey after 24-48 hours to prevent mold. Workers are small, so portion food appropriately, a few drops of sugar water and tiny insect pieces are sufficient.

Temperature and Seasonal Care

Lasius sonobei comes from southern Japan, a warm-temperate region. Keep the nest at 20-24°C for optimal brood development. They can tolerate slightly warmer conditions but avoid temperatures above 28°C. During summer, room temperature is usually appropriate. In winter, they require a diapause (hibernation) period of 2-3 months. Reduce temperature to 10-15°C by moving the colony to a cooler location like an unheated garage or refrigerator (not freezer). Do not feed during hibernation but keep the water tube filled. Resume normal temperatures and feeding in spring when the colony becomes active again. ^[1]

Colony Development and Growth

Lasius sonobei is a claustral founder, the queen seals herself in a chamber and does not leave to forage during founding. She lives entirely on her stored fat reserves while raising the first brood. This founding phase typically takes 4-6 weeks before the first workers (nanitics) emerge. The colony will grow gradually over the first year, reaching perhaps 50-100 workers by winter. Growth accelerates in the second year as the colony establishes. Mature colonies likely reach several hundred workers. Nuptial flights occur in August and September in the wild ^[1], so if you maintain a colony long-term, alates (reproductive ants) may appear during late summer.

Behavior and Temperament

This is a docile, non-aggressive species typical of the Lasius genus. Workers are small and yellow, often moving quickly through the outworld when foraging. They are not territorial or aggressive toward keepers. The main concern for antkeepers is their small size, workers are only 2.5-3.5mm, which means they can squeeze through very small gaps. Use cotton or proper stoppers on test tubes, and ensure any formicarium has tight-fitting connections. They are not known to sting and pose no danger to humans. In the wild, they forage for honeydew and small prey, often in association with aphid colonies. ^[1]

Frequently Asked Questions

References