Rearing of Wild Silkmoths: Comparative Biology and Life Cycles

Last Updated: January 28, 2026
Estimated reading time: ~8 minutes
Word count: 1,320

Non-mulberry sericulture depends heavily on the successful rearing of wild silkmoths in controlled or semi-controlled environments to ensure sustainable silk production. While traditional methods rely on outdoor rearing, which exposes larvae to predators and unpredictable weather, recent bio-systematic studies in Western Maharashtra have standardized indoor techniques for species like Attacus atlas, Actias selene, and the newly identified Antheraea mylitta kolhapurensis. This analysis delves into the comparative biology, nutritional ecology, and specific rearing requirements of these Saturniid moths, providing a blueprint for optimizing wild silk culture.

Key Takeaways

• Life Cycle Durations: A. atlas completes its life cycle in approximately 64 days, while A. mylitta kolhapurensis is faster, taking about 49 days.
• Rearing Success: A. mylitta kolhapurensis showed a high indoor rearing success rate of 45% on Terminalia catappa, compared to only 2% for A. atlas and A. selene.
• Host Plant Impact: Food consumption and assimilation rates vary significantly by instar and host plant, directly influencing cocoon weight.
• Instar Differentiation: Distinct morphological changes (tubercles, color spots) mark the transition between the five larval instars in all three species.
• Voltinism: A. selene and A. atlas exhibited trivoltine behavior (three generations per year) under laboratory conditions.

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Comparative Biology and Rearing of Wild Silkmoths

Biological Life Cycles of Saturniid Moths

Successful rearing of wild silkmoths requires a precise understanding of their life history stages. The thesis provides a detailed breakdown of the developmental timelines for three key species found in the Western Ghats. Unlike the domesticated Bombyx mori, these wild species exhibit significant variations in larval duration and pupal diapause based on environmental cues.

Attacus atlas (Atlas Moth)

The Atlas moth, known for its massive size, follows a life cycle where the egg stage lasts roughly 10 days. The larval period is split into five instars, totaling approximately 26-28 days.

• Larval Morphology: Early instars are white with black inter-segmental regions. By the fifth instar, the larva grows to over 11 cm, turning dark green with blue, fleshy tubercles. A unique feature is the presence of a “saddle” or distinct white powder on the dorsal surface.
• Pupation: The cocoon is spun within fresh leaves suspended by a strong silken stalk (peduncle). The pupal stage lasts about 28 days.

Actias selene (Moon Moth)

This species is distinct for its long-tailed hindwings and “pista” green color.

• Egg & Larva: Eggs hatch in about 8 days. The larvae are initially orange-brown with black bands, mimicking toxic insects. By the third instar, they turn green with orange/yellow tubercles. The total larval period is approximately 31-32 days.
• Pupation: The cocoon is whitish-grey, spun within leaves, but unlike the Atlas moth, it lacks a long peduncle. The pupal duration is roughly 20 days.

Antheraea mylitta kolhapurensis

This newly identified subspecies shows high potential for indoor rearing of wild silkmoths.

• Egg & Larva: Large, dorsoventrally flattened eggs hatch in 8 days. The larvae transition from dull brownish-yellow to a vibrant green. A key identifier is the presence of pearly lateral shining spots and a specific head capsule diameter increasing from 1.52 mm (1st instar) to 6.80 mm (5th instar).
• Pupation: It forms a robust, peduncled cocoon (unlike A. selene), with a pupal period of roughly 23 days.

“The mature larva spins its silk fibre around its body with the help of spinneret and tubercles… A. atlas silkworm undergoes pupation in an open type silk cage.” (Kavane, 2010, p. 124)

Fig: Comparative Life Cycle Duration (Days)

Developmental Stage	Attacus atlas	Actias selene	A. mylitta kolhapurensis
Incubation (Egg)	10	8	8
Larval Duration	~26.5	~31.5	~26
Pupal Duration	28	20	23
Total Life Cycle	~64.5	~59.5	~57

Professor’s Insight: The synchronization of the moth emergence with the availability of host plants is critical. In A. selene, the trivoltine nature means you must have a steady supply of fresh Terminalia leaves throughout the year to support three successive generations.

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Nutritional Ecology and Food Consumption

The efficiency of rearing of wild silkmoths is directly linked to food consumption, digestion, and assimilation. The thesis employed gravimetric methods to measure these indices, revealing that consumption increases exponentially during the fifth instar.

Consumption Patterns

• Fifth Instar Surge: Across all three species, the majority of leaf consumption occurs in the fifth instar. For A. selene reared on Terminalia arjuna, food consumption jumped from ~4g in the fourth instar to over 20g in the fifth instar.
• Host Plant Efficiency:
  • A. atlas showed optimal growth on Ficus carica (Angier), consuming approximately 66.89g of food total.
  • A. selene consumed significantly more (209.34g) when reared on T. arjuna, yet the conversion to cocoon shell weight was efficient.
  • A. mylitta kolhapurensis consumed about 145.34g on T. catappa, yielding a high shell ratio of 10.46%.

Growth Trends

Weight gain in larvae is not linear. It typically peaks mid-instar and drops just before molting (ecdysis) as the larva stops feeding to shed its cuticle.

• Negative Growth: Interestingly, the data recorded negative weight gain and respiration values on the specific days of molting, reflecting the physiological stress and cessation of feeding during this vulnerable period.

Student Note: Food Energy Assimilation (FEA) is calculated as Food Consumed minus Excreta. High FEA indicates the host plant is nutritious and digestible for that specific silkworm species.

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each section has been reworded uniquely for this post and reviewed by the Professor of Zoology editorial team. Direct thesis quotes remain cited; remaining content is original and educational.

Indoor Rearing Protocols and Success Rates

One of the study’s primary objectives was to evaluate if rearing of wild silkmoths could be transitioned from forests (in situ) to laboratories (ex situ) to improve survival rates.

Methodology

• Early Instars (1st-2nd): Reared in perforated plastic boxes to maintain high humidity and prevent desiccation. Fresh leaves were provided twice daily.
• Late Instars (3rd-5th): Transferred to larger metal (galvanized) trays covered with nylon nets to protect against parasitoids (like the Uzi fly).
• Environmental Control: Temperature was maintained at 28±2°C with humidity between 75-80%.
• Spinning: Mature larvae were provided with wooden rods and old twigs to simulate natural branches for cocoon anchorage.

Results of Indoor Rearing

The study highlighted a drastic difference in adaptability:

1. A. mylitta kolhapurensis: This subspecies proved highly adaptable to indoor conditions, achieving a 45% rearing success rate. This is a breakthrough compared to the typical 30-35% survival in outdoor rearings.
2. A. atlas* and *A. selene: These species performed poorly indoors, with success rates hovering around 2-5%. This suggests they are highly sensitive to handling, confinement, or specific micro-climatic conditions not fully replicated in the lab.

“The rearing success of A. mylitta var. kolhapurensis silkworms on food plants T.arjuna, T.tomentosa and T. catappa was 43%, 40% and 45% respectively under laboratory conditions.” (Kavane, 2010, p. 140)

Professor’s Insight: The high success of A. mylitta kolhapurensis indoors suggests it is a prime candidate for “domestication” or semi-domestication efforts, similar to how A. proylei was developed.

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Real-Life Applications

1. Conservation Breeding: The detailed life cycle data for A. atlas and A. selene allows zoos and butterfly parks to successfully rear these charismatic species for educational displays, despite their low commercial silk viability.
2. Year-Round Silk Production: By utilizing Terminalia catappa (Indian Almond), which retains leaves longer than some forest trees, farmers can extend the rearing season for A. mylitta, potentially adding an extra crop cycle.
3. Disease Management: The indoor rearing protocols described (plastic boxes, nylon nets) are practical low-cost methods for tribal rearers to protect early-instar larvae (“Chawki” worms) from viral and fungal pathogens before releasing them outdoors.
4. Ecotype Selection: Sericulturists can use the comparative data to select A. mylitta kolhapurensis for regions with heavy rainfall, as indoor rearing protects the fragile early stages from washing away.

Why this matters: Transitioning from purely wild harvest to controlled rearing stabilizes silk yield and protects wild populations from over-harvesting.

MCQs

1. Which host plant resulted in the highest indoor rearing success (45%) for Antheraea mylitta kolhapurensis?
A) Terminalia arjuna
B) Terminalia tomentosa
C) Terminalia catappa
D) Ziziphus jujuba
Correct Answer: C
Difficulty: Easy
Explanation: The results section explicitly states that rearing success on T. catappa was 45%, slightly higher than on T. arjuna (43%) or T. tomentosa (40%).

2. What is a distinct morphological feature of the 5th instar larva of Attacus atlas?
A) Orange-brown body with black bands
B) Dark green body with blue fleshy tubercles
C) Violet tubercles and a chocolate-colored head
D) Bright yellow body with long spines
Correct Answer: B
Difficulty: Moderate
Explanation: The thesis describes the 5th instar of A. atlas as dark green with lateral tubercles turning blue at the base and black at the tips.

3. In the context of rearing wild silkmoths, why were wooden rods introduced into the rearing trays for late-stage larvae?
A) To provide a food source
B) To increase humidity
C) To allow gripping for feeding and cocoon spinning
D) To prevent overcrowding
Correct Answer: C
Difficulty: Moderate
Explanation: The methodology section explains that wooden rods were introduced to simulate natural twigs, allowing larvae to grip while feeding and to provide a substrate for anchoring cocoons (peduncle formation).

4. Which of the following species showed the poorest adaptability to indoor rearing conditions in this study?
A) Antheraea mylitta kolhapurensis
B) Bombyx mori
C) Antheraea proylei
D) Attacus atlas
Correct Answer: D
Difficulty: Easy
Explanation: The study reports a very low rearing success rate of only about 2% for A. atlas under laboratory conditions, compared to 45% for A. mylitta.

FAQs

Q: How long is the incubation period for Attacus atlas eggs?
A: The incubation period for Attacus atlas eggs is approximately 10 days under laboratory conditions (27 ± 2°C).

Q: What is the primary difference in cocoon formation between Actias selene and Antheraea mylitta?
A: Antheraea mylitta spins a cocoon with a distinct, strong peduncle (stalk) for attachment to twigs, whereas Actias selene spins a cocoon without a peduncle.

Q: Can Terminalia catappa be used as a primary food plant for Tasar silkworms?
A: Yes, the study confirms Terminalia catappa (Desi Badam) is a potential food plant, supporting good larval growth and high shell ratios, making it a viable alternative to T. arjuna or T. tomentosa.

Q: Why do larvae lose weight at specific intervals during rearing?
A: Larvae lose weight and stop feeding just before molting (ecdysis) as they shed their old cuticle; the data reflects this as negative weight gain during specific days of the instar cycle.

Lab / Practical Note

Handling Molting Larvae: During the rearing of wild silkmoths, never forcibly remove larvae from leaves when they are stationary and holding their head up (a pose called “settling for molt”). They have anchored themselves with silk to pull out of their old skin. Disturbing them at this stage can be fatal or cause deformities. Wait until they have fully shed their skin and the head capsule turns from pale to the characteristic color of the next instar.

External Resources

• Central Silk Board – Vanya Silk – Information on non-mulberry silk resources in India.
• PubMed – Saturniidae Biology – Research articles on the physiology of wild silkmoths.

Sources & Citations

Kavane, R. P. (2010). Biosystematics of wild silkmoths from Western Maharashtra. (Doctoral dissertation, Shivaji University, Kolhapur). 1-304.

Source Note: Biological data, life cycle durations, and rearing success rates were verified using Chapters III, V, and VI, specifically Tables 1-3 and Figures 59-74 of the thesis.

Correction Invitation: If you are the author of this thesis and wish to provide updates or corrections to this summary, please contact us at contact@professorofzoology.com.