Omothymus

Omothymus is a genus of large, striking arboreal tarantulas found in Malaysia, Indonesia, and Singapore. Known for their vivid coloration and impressive size, some species can reach a leg span of up to 22 cm with a carapace length over 3 cm. These spiders are admired for their beauty and elusive nature, making them a fascinating subject for arachnid enthusiasts.

Introduction & Temperament Profile

The genus Omothymus comprises large, intensely colorful, and purely arboreal Old World tarantulas native to the dense, equatorial rainforests of Malaysia, Singapore, and Indonesia. Commonly referred to as “Earth Tigers,” this genus includes some of the most visually stunning yet intimidating tree-dwelling spiders in the world—most notably the famous Omothymus violaceopes (Singapore Blue).

• Behavioral Reality: Omothymus species are lightning-fast, deeply reclusive, and notoriously defensive. As Old World spiders, they possess no urticating hairs and rely entirely on their medically significant venom. They have a incredibly low tolerance for disturbance. When startled, they are just as likely to stand their ground, throw up an aggressive threat pose, and strike repeatedly as they are to bolt.
• Experience Requirement: They are strictly suitable for advanced, expert keepers only. Their combination of extreme speed, large size, and potent venom requires flawless handling protocols. Never attempt to handle an Omothymus species.

1. Hardware Shopping List (Everything You Need)

2. Enclosure Design & The Fossorial Sling Phase

• The Burrowing Sling: As spiderlings (slings) and small juveniles, Omothymus species display strong fossorial (burrowing) tendencies. They will dig deep tunnels into the substrate at the base of their cork bark. As they grow, they shift their home upwards, building a massive silk tube web that climbs up the cork bark.
• Adult Web Architecture: Adults weave thick, opaque curtains of silk mixed with bits of substrate (“dirt curtains”) behind their cork bark. They prefer deep, dark retreats.
• Front-Opening Only: Because they anchor their web tunnels to the top and sides of the tank, a top-opening enclosure will constantly tear their primary hide. Front-opening enclosures are mandatory.
• Cross-Ventilation Mandate: Because these spiders require higher ambient moisture, excellent cross-ventilation is vital. Stagnant, humid air will rapidly grow mold and bacteria, which is fatal to Asian arboreals. Air must flow horizontally through the sides of the enclosure.

3. Climate & Environmental Parameters

• Temperature: Keep ambient room temperatures between 23°C and 28°C. They are strictly tropical canopy species and do poorly if exposed to prolonged cold household temperatures.
• Heating Warning: Never use overhead heat lamps or ceramic heat emitters—they dry out the enclosure air too quickly. If your room drops below 19°C consistently, attach a low-wattage heat mat to the outside upper-side wall of the tank, regulated strictly by a digital thermostat.
• Humidity (75%–85%): They require a consistently humid environment. Maintain this by keeping the bottom half of the substrate damp (never a muddy swamp) and mixing in moisture-retaining sphagnum moss. Lightly mist the enclosure walls and fake leaves twice a week.

4. Feeding & Dietary Schedule

Omothymus species possess an explosive appetite and grow at an incredibly rapid pace, often reaching their massive adult sizes in under two years.

• Approved Prey: Crickets, Dubia roaches, and Red Runner roaches. Ensure the insect is appropriately sized (smaller than the tarantula’s body length).
• Sling Schedule: 1 small insect every 4 to 6 days.
• Juvenile Schedule: 1 to 2 medium insects every week.
• Adult Schedule: 2 to 3 large crickets or 1 large roach every 10 to 14 days.
• Molting Protocol: When preparing to molt, they will entirely seal the entrances to their silk tube tunnels. Never leave live insects in the enclosure during this time. Do not attempt to feed them until at least 10–14 days after they have shed their skin and their fangs have fully hardened to a jet-black colour.

5. Top Genus Species to Know

• The Singapore Blue (Omothymus violaceopes): The crown jewel of the genus. Females are massive (reaching up to 22+ cm leg spans) and display a breathtaking, brilliant metallic violet-blue color under light. Males are sexually dimorphic, turning a dull olive-green/yellow upon maturity.
• The Malaysian Violet (Omothymus schioedtei): A huge, beautiful species displaying dark green and bronze hues on the carapace, with striking dark violet/black legs and a beautifully patterned abdomen.
• The Maroon Earth Tiger (Omothymus rufus): A heavily built, slightly smaller species displaying rich, velvety reddish-brown and deep maroon tones.