Schwab's Razorjaw ant
Leptogenys schwabi
- Sci. Name
- Leptogenys schwabi
- Tribe
- Ponerini
- Subfamily
- Ponerinae
- Author
- Forel, 1913
- Common Name
- Schwab's Razorjaw ant
- Distribution
- Found in 2 countries
Introduction
Leptogenys schwabi is a medium-sized ponerine ant native to southern Africa (Eswatini, South Africa, and Zimbabwe). Workers are slender ants with elongated mandibles adapted for predation. Unlike most Leptogenys species which have single-queen colonies, L. schwabi forms polygynous colonies with multiple reproductive workers called gamergates. Colonies range up to 338 workers and nest in soft soils, under stones, or in rotting wood near the ground. They are specialized predators that hunt isopods, termites, and amphipods in groups. This species is unusual among ponerine ants for its group foraging behavior and the presence of multiple egg-laying workers within each colony.
Quick Summary
- Difficulty: Medium
- Origin & Habitat: Southern Africa (Eswatini, South Africa, Zimbabwe). Found in mixed mistbelt bush, closed riverine bush, and fig forest habitats, typically nesting in soft alluvial soils, shallow rocky soils, or rotting wood near the ground [1]. Also recorded in the western Soutpansberg Mountain Range of South Africa [2].
- Colony Type: Polygynous with gamergates, multiple reproductive workers (6-7 per colony) share egg-laying duties. Unlike most Leptogenys species which have single ergatoid queens, this species has retained the queen caste but relies primarily on gamergates for reproduction [1][3].
- Size & Growth:
- Queen: size data unavailable, no specific measurements found for this species
- Worker: size data unavailable, no specific measurements found for this species
- Colony: up to 338 workers in wild colonies, with an average of 184 workers in gamergate colonies [3][1]
- Growth: Moderate, colony growth is constrained by their specialized diet and group foraging requirements
- Development: Unknown, development time has not been directly studied for this species (Male production in wild colonies begins in late September, with adult males eclosing in early October.)
- Antkeeping:
- Temperature: Keep between 24-28°C. Running speed tests show they are active from 20-35°C with optimal performance around 28°C [4]. A slight thermal gradient allows them to regulate body temperature.
- Humidity: Moderate to high. As ground-nesting ants from forest habitats, they prefer moist but not waterlogged substrate. Keep nest substrate consistently damp with some drier areas for escape.
- Diapause: Unknown, true hibernation has not been studied for this species. Southern African populations may experience mild winter slowdown rather than full diapause.
- Nesting: Ground-nesting species that does well in naturalistic setups with soil or plaster nests. Provide moist substrate for nesting chambers and a foraging area. They will nest in soft soil, under flat stones, or in rotting wood in captivity.
- Behavior: These ants are active group foragers that hunt in small parties of 4-6 workers. They use a loose formation with frequent leader changes rather than tight tandem running. Workers are predatory and specialize on isopods, termites, and other small arthropods. They have a functional sting typical of Ponerine ants, painful but not dangerous. Escape risk is moderate, they are active foragers but not extreme escape artists. Provide a well-secured outworld.
- Common Issues: specialized diet means colonies often fail if not provided appropriate live prey (isopods, termites), group foraging requires space and multiple foragers, small colonies may struggle to hunt effectively, polygynous structure means removing gamergates can disrupt colony reproduction, moisture requirements can lead to mold issues if ventilation is poor, slow colony growth compared to common pet species may frustrate beginners
Nest Preferences and Housing
Leptogenys schwabi is a ground-nesting species that naturally nests in soft alluvial soils, shallow rocky soils, or rotting wood near the ground surface. In the wild, nests in alluvial soil were less than 30cm deep with no obvious passages, while nests in dry rocky soils included chambers beneath stones connected by passages extending to 45cm depth [1]. In captivity, they do well in naturalistic setups with a soil chamber or plaster nest that maintains moisture. Provide a nest chamber with damp substrate deep enough for the colony to create galleries. The outworld should be spacious enough for group foraging expeditions. Use a well-secured escape barrier since these active foragers will explore any gaps.
Feeding and Diet
This is a specialized predator that primarily hunts isopods (Philoscia sp.), termites (Odontotermes latericius), and amphipods in the wild. Termites become especially important during September-October when rains increase termite foraging activity [1]. In captivity, you should replicate this specialized diet as closely as possible. Offer live isopods regularly, along with termites or other small arthropods. They are not typical 'feed them anything' ants, their hunting behavior is a key part of their natural history. Some keepers report success with small crickets and fruit flies, but these should supplement rather than replace their preferred prey. Remove uneaten prey promptly to prevent mold.
Temperature and Seasonal Care
These ants are active within a temperature range of 20-35°C, with peak foraging activity around 28°C [4]. Provide a thermal gradient so workers can regulate their body temperature by moving between warmer and cooler areas. A heating cable on one side of the nest works well. In their native range (southern Africa), temperatures are warm year-round with mild winters. While they may not require a true hibernation period, reducing temperatures slightly during winter months (to around 22-24°C) mimics their natural seasonal cycle. Male production in wild colonies begins in late September, suggesting seasonal breeding patterns tied to rainfall [1].
The Gamergate Reproductive System
Leptogenys schwabi has an unusual reproductive system among ants, they are polygynous with gamergates. This means multiple workers (6-7 out of the colony) have active ovaries and can mate to become reproductive [1]. Unlike typical ant colonies with one queen, here several workers share egg-laying duties. This is regulated by pheromones, when gamergates are present, other workers have suppressed reproductive physiology. If you remove the gamergates, previously non-reproductive workers may begin laying eggs. Studies showed 7 workers out of 260 from one colony and 6 out of 146 from another colony were mated with active ovaries containing oocytes and corpora lutea [1]. The colony has retained the queen caste, but winged queens are unknown, reproduction happens primarily through gamergates.
Foraging Behavior
These ants forage in groups of 4-6 workers using a loose formation with frequent leader changes. Individual workers often wander up to a meter from the group, which can cause the formation to break down without encountering prey [1]. This is different from the tight tandem running seen in many ant species. They are active hunters that search for isopods and termites across the forest floor. The entrances of natural nests are surrounded by the skeletons of their prey, a good sign that your colony is hunting successfully. In captivity, provide a spacious foraging area and consider scattering prey to encourage natural hunting behavior rather than placing food directly at the nest entrance.
Frequently Asked Questions
Can I keep Leptogenys schwabi in a test tube?
A test tube is not ideal for this species. They are ground-nesting ants that need moist soil or substrate for nesting chambers. They also forage in groups and need space to hunt. A naturalistic setup with a soil chamber or plaster nest works much better. Use a test tube only as a temporary holding container.
What do Leptogenys schwabi ants eat?
They are specialized predators that need live prey. Their primary food in the wild is isopods, termites, and amphipods. In captivity, offer live isopods regularly along with termites or other small arthropods. They are not scavengers and typically ignore dead food. This specialized diet makes them more challenging to keep than typical ant species.
How long does it take for Leptogenys schwabi to produce first workers?
Exact development time is unknown for this species. Ponerine ants typically take 2-3 months from egg to adult worker, but specific data for L. schwabi is not available.
Can I keep multiple queens together in a Leptogenys schwabi colony?
Yes, this is normal for the species. Unlike most Leptogenys which have single-queen colonies, L. schwabi is naturally polygynous with multiple reproductive workers (gamergates). The colony functions with several egg-laying workers rather than a single queen. Do not combine unrelated foundress colonies, they should already contain the gamergate structure.
Are Leptogenys schwabi ants good for beginners?
No, this species is not ideal for beginners. Their specialized predatory diet (requiring live isopods and termites), moderate temperature needs, and longer development time make them more challenging than common beginner species. They are better suited for antkeepers with some experience who can provide appropriate live prey.
What temperature do Leptogenys schwabi ants need?
Keep them between 24-28°C. Research shows they are active from 20-35°C with peak performance around 28°C [4]. A thermal gradient allows them to regulate their body temperature.
How big do Leptogenys schwabi colonies get?
Wild colonies range up to 338 workers, with an average around 184 workers in gamergate colonies [3][1]. They are not among the largest ant colonies, but they are active foragers that need space.
Do Leptogenys schwabi need hibernation?
True hibernation is uncertain for this species. As a southern African ant, they experience mild winters rather than harsh cold. You can provide a slight temperature reduction in winter (around 22-24°C) but full diapause is likely not required.
Why are my Leptogenys schwabi dying?
The most common causes are inadequate diet (not providing enough live isopods/termites), improper humidity (too dry or too wet), and temperature issues. They are specialized predators, colonies often fail when fed only typical ant foods. Ensure you have an established prey culture. Also check for mold in the nest and ensure proper ventilation.
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