Bolivian Dwarf Tarantula

Cyriocosmus perezmilesi Care Guide

Bolivian Dwarf Tarantula

Revision Date: March 2025

Introduction

Cyriocosmus perezmilesi, commonly referred to as the Bolivian Dwarf Tarantula, is a fascinating New World terrestrial species native to Bolivia and surrounding regions in South America. It is one of the smallest tarantulas in the hobby, with females reaching only about 2 inches in diagonal leg span and males typically being even smaller. Despite its diminutive size, this species exhibits rapid growth and an impressive feeding response, making it a favorite among dwarf tarantula enthusiasts. Like other Cyriocosmus species, C. perezmilesi features a distinctive heart-shaped marking on its abdomen, adding to its unique appeal.

Quick Species Snapshot

Scientific Name: Cyriocosmus perezmilesi
Common Name: Bolivian Dwarf Tarantula
Type: Terrestrial (with semi-arboreal tendencies)
Category: New World
Endemic Location: Bolivia
Body Length: Approximately 0.8” (2 cm)
Diagonal Leg Span (DLS): Approximately 2” (5 cm)
Urticating Hairs: Yes
Growth Rate: Fast
Life Expectancy:

• Females: Up to 7 years

• Males: Approximately 2 yearsRecommended

Experience Level: Beginner

What Makes Cyriocosmus perezmilesi So Special?

The Bolivian Dwarf Tarantula is one of the most visually appealing dwarf tarantulas, boasting a golden carapace, dark legs with subtle striping, and a pronounced heart-shaped marking on the abdomen. Its compact size, rapid growth, and lively behavior make it an excellent choice for those with limited space or an interest in smaller tarantulas. Despite its small stature, C. perezmilesi is known for its strong feeding response and active enclosure behavior, making it an engaging species to observe.

Taxonomy, Etymology & Natural Environment

Cyriocosmus perezmilesi, commonly known as the Bolivian Dwarf Beauty Tarantula, is a captivating species within the Theraphosinae subfamily. First described in 2007 by Radan Kaderka, this species is notable for its small size, intricate markings, and vibrant coloration. It features a copper-colored carapace and a black abdomen adorned with a heart-shaped urticating patch and eight vertical lines extending toward the patch, making it one of the most visually striking members of its genus.

The genus name Cyriocosmus is derived from the Greek words "kyrios", meaning "lord" or "master," and "kosmos", meaning "ornament" or "decoration," referencing the intricate markings characteristic of the species in this genus. The species name perezmilesi honors Dr. Fernando Pérez-Miles, a renowned Uruguayan arachnologist recognized for his extensive contributions to tarantula taxonomy and research.

Natural Range & Habitat

Native to Bolivia, C. perezmilesi inhabits tropical rainforests, where it thrives in warm, humid environments. As a fossorial species, it constructs deep burrows in the forest floor, using them as a retreat for protection from predators and environmental extremes. In the wild, this species remains hidden for much of the day, emerging at night to ambush prey.

Given the dense vegetation and humid conditions of its native habitat, C. perezmilesi requires moderate to high humidity levels in captivity, though proper ventilation is essential to prevent mold growth and excessive moisture buildup. This species is also known to create intricate burrows lined with silk, making a deep substrate essential for replicating its natural environment.

Behavior & Temperament

Like most Cyriocosmus species, C. perezmilesi is shy and reclusive, preferring to remain within its burrow rather than actively exploring the enclosure. It is generally not defensive, choosing to retreat at high speed when disturbed rather than stand its ground. While it does possess urticating hairs, it rarely uses them unless it feels threatened.

Despite its small size, C. perezmilesi has a strong feeding response, often striking at prey with enthusiasm. However, due to its delicate nature and fast movements, handling is strongly discouraged, as even a short fall could be fatal. Keepers are best served by observing this species within a well-designed enclosure where its natural behaviors can be appreciated.

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 1/3 to 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: Maintain ambient temperatures between 68°F and 76°F (20°C to 24°C).

• Humidity: Aim for moderate humidity with a moisture gradient in the substrate.

• Water Dish: Always provide fresh water in a small dish.

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.

Breeding Cyriocosmus perezmilesi in Captivity

Breeding Cyriocosmus perezmilesi (Bolivian Dwarf Tiger Tarantula) is a fascinating process due to their small size, quick reproductive cycle, and high egg sac production. As a less commonly bred species, successful pairings help ensure strong captive populations while keeping wild specimens undisturbed.

Sexual Maturity & Pairing

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

• Female Maturity: Females take slightly longer, typically 2–3 years, before reaching full reproductive maturity.

• Pre-Pairing Preparation: We should ensure the female is well-fed before introducing the male to reduce defensive reactions. Increasing humidity slightly before pairing may improve receptivity.

Mating Process

• Introduce the male at night, as they are more active in dim lighting.

• 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 post-mating.

Egg Sac Production

• If fertilized, the female will produce 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 proper ventilation to prevent mold.

• The egg sac typically contains 50–150 eggs, which is a 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. perezmilesi spiderlings are tiny and delicate, requiring precise humidity control.

• 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 rapid metabolism.

Challenges & Considerations

• Tiny and fragile spiderlings require controlled humidity and careful feeding schedules.

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

• Short male lifespan, usually 6–12 months after maturity, means breeding attempts should be made as soon as possible.

With its striking tiger-like markings and small size, Cyriocosmus perezmilesi is a fascinating species that deserves more attention in the hobby. By focusing on captive breeding efforts, we can ensure healthy, self-sustaining populations while protecting wild specimens. Every successful breeding project contributes to the long-term future of this species in captivity and strengthens the hobby as a whole.

Final Thoughts

The Bolivian Dwarf Beauty Tarantula (Cyriocosmus perezmilesi) is a fascinating species that showcases the elegance and intricacy of dwarf tarantulas. Its small size, striking coloration, and burrowing behavior make it a standout species for enthusiasts who appreciate observing natural behaviors rather than handling. While not a display tarantula in the traditional sense, its strong feeding response, intricate web-lined burrows, and occasional surface activity provide plenty of intrigue for patient keepers.

As with all dwarf tarantulas, proper substrate depth, humidity control, and prey sizing are essential to maintaining a healthy, thriving specimen. Though it may be a more reclusive species, its unique markings and delicate beauty make it a rewarding addition to any collection, especially for those interested in expanding into the world of smaller, lesser-known tarantulas. With the right setup and care, C. perezmilesi will flourish in captivity, offering a fascinating glimpse into the lives of these intricately patterned, burrow-dwelling tarantulas.

Additional Recommendations

For enclosures, consider Tarantula Cribs (affiliate code TTC10 for 10% off). Use Terra Aranea by The Bio Dude for substrate and other bioactive supplies. For tarantulas, check out Spider Shoppe (use code TTC10 for 10% off). Visit the Dealer & Discounts section on my website for more trusted sellers and discount codes.