Silkworm Breeding: Ultimate How-To

Silkworm Breeding: Ultimate How-To

Aug 11th 2021

How to Raise Silkworms

Silkworms are one of the most fascinating feeder insects available for reptile owners. With a history stretching back thousands of years in Chinese culture, they have now been domesticated all over the world for purposes ranging from silk production to feeding lizards and turtles! Their versatility has allowed them to be one of the richest sources of nutrition for your pet, and - with the right experience - can be quite a fun pet to keep as well!

What is a Silkworm?

The silkworm, like most feeder species, is known worldwide by a misnomer since it is not a worm in the slightest. Just like the mealworm, this insect is the third developmental stage of its true species, the silkworm moth, Bombyx mori. The silkworm is a staple in ancient Chinese history, having been used for thousands of years for silk production (also known as "sericulture").

They are currently studied internationally in the field of "bionics," a scientific discipline dedicated to the study of animal physiology as an inspiration to engineering. For years, scientists have observed these insects in laboratory environments to discover just how they produce their silk and how we can apply it to human life.

The species has been distributed throughout the world and is now completely domesticated, unable to be found in the wild.

The silk moth is a medium-sized insect: Its wingspan is about 2 inches wide (females are larger than males, so the maximum is a representation of their body size), and it has a hefty body that is covered in coarse bristles. While its body is typically somewhere between a blond to light brown color, it has pattern of dark bands that run across its entire frame. The wings mimic this color scheme, being cream-colored with a network of dark brown veins decorating them.

Aside from their historical significance, silkworm behavior is quite intriguing as well. They only live for about 2-3 days in adulthood, during which time they do not have mouthparts (or extremely small mouthparts). Surprisingly, they cannot fly either. Still, they manage to function at a capacity in which they are capable of reproducing.

When courting a female, males perform what is known as a type of "flutter dance," where they excitedly mobilize their wings to gain the attention of the females. This behavior is a direct response to the female's release of the pheromone, "bombykol," that communicates to the males that they are ready to mate and reproduce. Once fertilized, the females can lay between 300-500 eggs at once.

Life cycle of the Silkworm

The life cycle of the silkworm follows the same pattern of many popular feeder insects. They go through a complete metamorphosis, meaning they have four (or more, depending on the species) distinct life stages, the juvenile stages being unrecognizable in comparison to the adult. The life cycle of the silkworm is as follows:

  • Egg: As we mentioned above, the silkworm female can lay up to 500 eggs at a time in her short adult life. Within 1-2 weeks, the eggs will hatch - that is, if they are kept at a consistent temperature of 75-85F.
  • Larva (caterpillar): Once hatched, the new silkworm larvae will be only 0.08-0.12" in length. But don't be fooled! They have large appetites for their size (85% of the eating they'll do throughout their entire lives is done in this stage!). During the larval stage, the silkworms have a great deal of growing to do in order to prepare for future development phases. As they focus on ingesting as many nutrients as possible, they go through distinct larval growth stages known as "instars." There are five instars altogether, separated by four molting events. To progress healthily, the larvae will need an abundant supply of mulberry leaves, a plant species native to their home in China. Throughout the majority of this developmental period, the larvae are characterized by a pale body and a caudal (posterior) horn. It ultimately reaches its recognizable caterpillar stage at its maximum 3". This growth occurs over a maximum of 45 days, and by the end, its silk glands now account for about 1/4 of its body weight.
  • Pupa: Once it is ready to enter its pupal stage, the silkworm must prepare to spin its cocoon using the silk it has stored away during the larval stage. It produces a single strand of white or yellow silk about 1000 yards long to construct its cocoon, the final product being just about the size of a cotton ball. As it rests inside the cocoon, no longer eating or drinking, it completes its development to later emerge as the adult silk moth.
  • Adult (also known as "Imago"): Once emerged, the silk moth is a hairy little thing. Males will actively seek out the females by following the scent of their pheromones in order to mate. Recall that their adult lifespan is only about 2-3 days, so this is essentially their only purpose during this life stage.

Where Are Silkworms From?

Silkworms are native to China, where they were cultivated for silk more than 5,000 years ago. During the 11th century, European traders began their distribution throughout the entire world, taking both mulberry seeds and silkworm eggs to give them as close to a natural environment as possible without having to remain in their home country. Although silk is now largely produced synthetically, the silk moth is still put to work in major countries including China, Japan, Spain, France, and Italy.

Because they have been so extensively domesticated, silkworms are unable to exist in the wild anymore. Recall that they are unable to fly: This is not a trait that developed in the wild, but due to intense domestication over the centuries. With that said, silkworm habitats are now entirely crafted by humans, simply by planting and maintain an orchard of mulberry trees (or collecting the fresh leaves of mulberry trees and placing them inside of a closed container.

Nutritional Value of Silkworms

Silkworms are claimed by many to be one of the best feeder insects you can feed your pet. They are packed with minerals including sodium, magnesium, iron, and vitamins B1, B2, and B3, and are regarded by numerous experts to be more nutritious than almost any other feeder insect on the market.

They are also one of the easiest insects to feed your pet due to their soft bodies and inability to jump or bite. They are slow in their movements as well, making it quite easy for your reptile to catch them (also ideal for younger reptiles). They're also guaranteed to live longer in your animal's enclosure than insects such as crickets, for example, ensuring that your pet will have the chance to munch on all the silkworms you give it.

How to Raise Silkworms

Raising silkworms is quite a challenging affair, and should only be left to those who are experienced in keeping a colony of insects. Despite having been domesticated for several centuries now, silkworms are still quite particular in their dietary and habitat needs, even in captivity.

1. Housing Your Silkworms

When you have gathered your silkworm eggs, you will need to set up the perfect housing arrangement for them - for this species, that means loads of fresh mulberry leaves. You can either grow the mulberry tree yourself (it is a highly adaptive species, able to grow in all sorts of soil and environmental conditions), or simply purchase sets of mulberry leaves from a supplier. Place the eggs in a small dishpan or shoebox and store it in a warm area that is well ventilated. (At this stage, you will not need to add substrate - that only becomes necessary at the larval stages, onward.)

You must take care to keep the eggs (and all other life stages) out of direct sunlight and protected from drafts, to avoid extreme temperatures. Over several days as the eggs are acclimating to their enclosure, gradually increase the temperature of the box until it reaches a maximum of 68-77F, and keep it consistent from there on. Depending on the temperature and humidity levels, it can take anywhere between 3-10 days for your silkworms to hatch.

2. Care and Maintenance

Now that your silkworms have hatched, you must add the substrate, which will double as their feed. Gather your mulberry leaves and select only the most tender of the bunch. Wash the leaves thoroughly to ensure the silkworms do not ingest any chemicals and cut them into 1/4" squares. Sprinkle the feed evenly throughout the box, and voila! They are ready to feed as they produce loads of high-quality silk while growing into yummy treats for your pets!

Silkworms are among the most fascinating insects in the world, much more in the world of feeder insects. Although they are quite a challenge to raise, this insect is incredibly nutritious, offering a multitude of vitamins and minerals for your beloved reptile, making them very much worth the effort for experienced owners.