Cyriocosmus leetzi Care Guide

The Colombian Dwarf Tarantula

Revision Date: March 2025

Introduction

Cyriocosmus leetzi, commonly known as the Colombian Dwarf Tarantula, is a stunning New World dwarf species native to Colombia. This species is part of the Cyriocosmus genus, known for its small size, rapid growth, and striking abdominal patterns. While not as widely kept as C. elegans or C. perezmilesi, C. leetzi stands out with its unique coloration and reclusive yet active nature.

Despite its small size, this tarantula displays fascinating behaviors, frequently alternating between burrowing and webbing. It is an excellent addition for experienced keepers looking to work with dwarf species, though its delicate size makes it a less ideal choice for beginners.

Quick Species Snapshot

• Scientific Name: Cyriocosmus leetzi

• Common Name: Colombian Dwarf Tarantula

• Type: Terrestrial (with semi-arboreal tendencies)

• Category: New World

• Endemic Location: Colombia

• Body Length: 0.75” (2 cm)

• Diagonal Leg Span (DLS): 2” (5 cm)

• Urticating Hairs: Yes

• Growth Rate: Fast

• Life Expectancy:

  • Females: Up to 8 years

  • Males: 2–3 years

• Recommended Experience Level: Intermediate

What Makes Cyriocosmus leetzi Special?

Cyriocosmus leetzi is a unique species within the Cyriocosmus genus due to its subtle yet beautiful coloration and active behavior. While it may not be as vibrant as C. elegans, its earthy tones and distinct abdominal pattern make it an eye-catching species. This tarantula exhibits a combination of burrowing and surface activity, making it an interesting species to observe.

Taxonomy, Etymology & Natural Environment

Cyriocosmus leetzi, commonly known as the Colombian Dwarf Tiger Tarantula, is a rare and visually striking species within the Theraphosinae subfamily. First described in 1994 by Pérez-Miles, C. leetzi is a lesser-known member of the Cyriocosmus genus but shares the group's characteristic metallic carapace, bold black and bronze markings, and vibrant abdominal patterning. Its diminutive size and intricate coloration make it a fascinating species for experienced keepers interested in dwarf tarantulas.

The genus name Cyriocosmus is derived from the Greek words "kyrios", meaning "lord" or "master," and "kosmos", meaning "ornament" or "decoration," referencing the intricate patterns found across species in this genus. The species name leetzi honors German entomologist Dr. Klaus Leetz, recognizing his contributions to arachnology.

Natural Range & Habitat

Cyriocosmus leetzi is native to Colombia, where it inhabits tropical rainforests and lowland jungle regions. As a fossorial species, it constructs deep burrows in soft, humid soil, using them for protection from predators and extreme environmental conditions. These burrows also serve as ambush points for unsuspecting prey. Unlike arboreal tarantulas or opportunistic burrowers, C. leetzi relies heavily on its burrow for survival, rarely venturing far from its retreat.

The natural environment of C. leetzi consists of warm, humid conditions, with a substrate that retains moisture but drains well to prevent oversaturation. In captivity, mimicking these environmental factors is key to maintaining the health and longevity of this species.

Behavior & Temperament

Like many other Cyriocosmus species, C. leetzi is skittish and reclusive, preferring to stay within its burrow rather than actively exploring its surroundings. It is not a defensive species but will retreat at high speeds when disturbed. While bites from C. leetzi are exceedingly rare, this species is incredibly fragile due to its small size, making handling highly discouraged. Even a short fall can be fatal.

Despite its reclusive nature, C. leetzi is an active hunter, often exhibiting a strong feeding response when prey approaches its burrow entrance. Observing this species in a well-designed enclosure allows keepers to witness its burrowing, ambushing, and webbing behaviors without unnecessary disturbance.

Housing & Substrate – Semi-Arboreal Setup

Spiderlings

• Enclosure Size: Use a small acrylic enclosure (e.g., Sling Crib, 3" Tarantula Cube, Small Slider Crib, Small Cuboid, Terrestrial Sling Crib, Slider Crib Mini, or Cuboid Mini) that is no smaller than three times the tarantula’s leg span.

• Substrate: Fill at least 2/3rds of the enclosure with Terra Aranea by The Bio Dude.

• Humidity: Maintain a slightly damp substrate (but not swampy) by offering a small water dish or gently dripping water on one corner about once a week.

Juveniles

• Enclosure Size: Use a medium enclosure (e.g., Medium Slider Crib, 6" Tarantula Cube, 8" Tarantula Cube, or Medium Cuboid) that is at least 3–4× the tarantula’s leg span.

• Substrate: Fill the enclosure 1/2 full with Terra Aranea by The Bio Dude. This depth allows for effective burrowing and minimizes the risk of injury from falls.

• Humidity: Keep the substrate mostly dry with a full water dish; occasionally overflow one corner to create a slightly damp area.

• Additional Features: Provide a half cork bark round for a secure hide and include vertical branches, cork bark pieces, or small fake plants as web anchors to facilitate natural web tunnel construction.

Adults

• Enclosure Size: Use a large enclosure (e.g., Large Slider Crib, 12" Cube Switch, 12" Cube, 18" Cube, or Terrestrial XL) that is at least 3× the tarantula’s leg span (ideally 4–5× for enhanced natural behavior, while still considering escape risks).

• Substrate: Fill the enclosure 1/3 to 1/2 full with Terra Aranea by The Bio Dude to provide ample depth for burrowing while reducing fall distance.

• Additional Features: Include a secure hide (preferably a half cork bark round), a shallow water dish, and tasteful decorations such as vertical branches or cork bark pieces leaned diagonally. Ensure the enclosure is a horizontal rectangle (wider than it is deep) with secure ventilation and a tight, secure lid to prevent escapes.

Note: "Semi‑arboreal" is not an official behavioral classification but rather a descriptive term used in the hobby to design enclosures that allow a tarantula to display some climbing and web anchoring behavior without exposing it to dangerous falls. For semi‑arboreal species, the enclosure is typically a square or horizontal rectangle rather than a tall arboreal setup. This design minimizes fall distance and risk of injury. Never use an arboreal enclosure for a species that is not truly arboreal.

Affiliate: Please use Tarantula Cribs (affiliate code TTC10) and Terra Aranea by The Bio Dude for substrate.

Temperature & Humidity

• Temperature: 70–78°F (21–26°C)

• Humidity: 60–70%

• Water Dish: Keep one filled and overflow occasionally to maintain a moisture gradient.

Feeding Schedule

Spiderlings

• Frequency:
  Feed twice a week.

• Prey:
  Offer small prey such as flightless fruit flies, confused flour beetles, or pre-killed tiny crickets/roach nymphs. Remove any uneaten prey after 24 hours. increase the size of the prey as the spider grows. Prekill any prey that is over 2/3 the size of the sling. For more detailed information on feeding spiderlings, watch this video: How To Feed Spiderlings & Scorplings (Baby Tarantulas & Scorpions)

• Post-Molt:
  Wait 24–48 hours after a molt before feeding. Ensure that the tarantula’s fangs are solid black and its exoskeleton is not soft or shiny.

Juveniles

• Frequency:
  Feed every 7–10 days.

• Prey:
  Provide 2–3 small to medium crickets or a medium Dubia roach.

• Feeding Guidelines:

  • If the abdomen is thinner than the widest part of the carapace, feed more prey more often.

  • If the abdomen is wider than the carapace, feed less prey, less often.
    This strategy helps prevent obesity, which can lead to molting complications or increase the risk of an abdomen rupture from even a small fall.

• Post-Molt:
  Wait 3–7 days after a molt before feeding, ensuring that the tarantula’s fangs are solid black and its exoskeleton is fully hardened.

Adults

• Frequency:
  Feed every 2–3 weeks (or as needed).

• Prey:
  Offer 4–5 large crickets or one large Dubia roach.

• Feeding Guidelines:

  • If the abdomen is thinner than the carapace’s widest part, increase feeding frequency.

  • If the abdomen is wider than the carapace, reduce feeding frequency.
    This is crucial to avoid obesity, which can interfere with proper molting or cause dangerous issues such as an abdomen rupture.

• Post-Molt:
  Wait 5–10 days after a molt before feeding, ensuring that the tarantula’s fangs are solid black and its exoskeleton is fully hardened.

Behavior & Temperament

Cyriocosmus leetzi is generally reclusive, preferring to remain hidden in its burrow or behind webbing. While not aggressive, it can be skittish and quick to retreat when disturbed. Handling is not recommended due to its delicate size and potential for rapid movements.

Breeding Cyriocosmus leetzi in Captivity

Breeding Cyriocosmus leetzi (Leetz's Dwarf Tarantula) requires patience and careful handling due to their tiny size, fast movements, and delicate spiderlings. Since this species is not as commonly bred in captivity, every successful pairing helps maintain sustainable captive populations while ensuring that wild specimens remain undisturbed.

Sexual Maturity & Pairing

• Male Maturity: Males mature quickly, typically within 1–2 years, developing enlarged pedipalps for sperm transfer.

• Female Maturity: Females take 2–3 years to reach reproductive maturity.

• Pre-Pairing Preparation: We should ensure the female is well-fed before introducing the male to prevent defensive behavior. Some breeders report higher success rates when humidity is slightly increased before pairing.

Mating Process

• Introduce the male at night, as this species is more active in low light.

• The male will drum on the substrate or webbing to signal his presence.

• If receptive, the female may drum back or remain still, allowing the male to approach and insert his emboli.

• Once mating is complete, the male should be removed immediately, as females may become defensive afterward.

Egg Sac Production

• If fertilized, the female will begin producing an egg sac 4–8 weeks after mating.

• Maintain temperatures around 75–80°F (24–27°C) with humidity levels of 65–75 percent, ensuring good airflow to prevent mold.

• The egg sac typically contains 50–150 eggs, which is a relatively high number for a dwarf species.

Egg Sac Handling (Optional)

• Some breeders choose to pull the egg sac after 30–40 days for artificial incubation.

• If left with the mother, first instar spiderlings will emerge in 6–8 weeks and molt into second instar within 3–4 weeks.

Raising Spiderlings

• C. leetzi spiderlings are extremely small and fast, requiring micro enclosures with stable humidity.

• Provide ventilated enclosures with a shallow layer of moist substrate to prevent desiccation.

• Feed them pre-killed pinhead crickets, flightless fruit flies, or small roaches every 2–3 days due to their fast metabolism.

Challenges & Considerations

• Tiny and fragile spiderlings require precise humidity and feeding schedules to prevent desiccation.

• Fast movements make pairing and handling trickier than with larger species.

• Male lifespan is short, typically 6–12 months after maturity, so breeding should be attempted as soon as possible.

Cyriocosmus leetzi is not commonly bred in captivity, which makes every successful pairing important for maintaining healthy, self-sustaining populations. By focusing on captive breeding efforts, we can help ensure that this fascinating species remains available in the hobby without impacting wild populations. Every breeding success contributes to the long-term sustainability of this species in captivity.

Final Thoughts

Among Cyriocosmus species, C. leetzi is an interesting contrast to its relatives. Here’s how it compares:

• Size: Like C. elegans, C. leetzi is a true dwarf species, reaching about 2” in DLS, making it smaller than species like C. perezmilesi.

• Coloration: C. elegans is known for its high-contrast markings and heart-shaped pattern, while C. leetzi has more subtle tones.

• Temperament: C. leetzi tends to be more reclusive than C. perezmilesi and C. elegans, spending more time hidden in its burrow.

• Burrowing vs. Webbing: While C. elegans and C. leetzi both burrow, C. perezmilesi exhibits more pronounced semi-arboreal tendencies.

Overall, Cyriocosmus leetzi is a fascinating, lesser-known species within the genus. It’s a great option for keepers who enjoy observing intricate burrowing and webbing behavior in a compact, manageable species.

Additional Recommendations

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• For enclosures, consider Tarantula Cribs (use code TTC10 for 10% off).

• Use Terra Aranea by The Bio Dude for substrate.

• For tarantulas, check out Spider Shoppe (use code TTC10 for 10% off), and visit the Dealer & Discounts section on my website for a curated list of recommended dealers and discount codes.