A Brief History of Silk and the Silkworm
A legend unraveled
According to folklore, silk was discovered in the year 2640 B.C. by a Chinese Empress named, Lei Zu. Apparently, Lei Zu had been strolling through her garden when a strange-looking cocoon dropped into her teacup. As she picked it out of the cup, the cocoon began to unravel into fine glistening threads. Struck by the beauty of these threads, Lei Zu looked up to see where the cocoon had come from. Above her, hoards of tiny caterpillars (silkworms, as it turns out) were crawling around the branches of a mulberry tree. Not only did our industrious little Empress figure out that the cocoon had come from these caterpillars, but she decided to keep this discovery secret from the rest of the world — with the death penalty awaiting anyone who revealed the source of the threads. Don't you just love Empresses?
And so it was that the royal family of China kept the secret of silk firmly to themselves for about 2500 years — their monopoly only ending when two monks who had recently visited China arrived in Constantinople, claiming to have discovered the wormy origin of the much sought-after fabric. The Emperor of Constantinople immediately ordered the monks to return to China and bring him back a collection of the caterpillars so he could go into silk production himself and end China's control over the supply. The monks agreed and managed to escape China with a collection of silkworm eggs and Mulberry shoots hidden in a specially-made walking stick. Don't you just love monks.
Although the route the monks took from China to Constantinople has now become known as the 'Silk Road', the story associated with it is considered far more legend than fact. Although silk was indeed discovered in China, remnants of silk garments have been found in Chinese tombs that date back 8,500 years to the Neolithic period. While that's much further back in history than Lei Zu's story, it's a testament to the perseverance and brutality of China's ruling classes that they managed to keep the silk production process (sericulture, as it's known) secret until about 200 B.C. It was then that China's neighbor, Korea, learned the process, with India following a couple of centuries later. With the secret now well and truly out of the silk bag, the glistening fabric that was once the dominion of Emperors and Empresses was well on its way to the medieval K-Marts of the planet — and all thanks to the hard work of a tiny little caterpillar.
How is silk made?
The silkworm is the larva of the silk moth (Bombyx mori). To create the cocoon that the worm needs in order to transform into an adult moth, it secretes a water-insoluble protein fiber (largely made up of fibroin) from its glands. It's this fiber that we call silk — its glistening appearance being a result of the fiber's prism-like structure which refracts light and produces that much-desired shimmering spectrum of colors.
Although there are many insects and arachnids that produce silk (a spider's web is nothing but silk) it's the cocoons of silkworms that are generally used in the production of commercial fabric. Each cocoon is made up of a single filament of silk between one thousand, and three thousand feet long (yes, you read that right). The cocoons are boiled then brushed in order to locate the outside end of the filament, after which the filament is wound onto a reel — with forty-eight filaments being used to make one silk thread.
To put it another way, you'll need to harvest about a thousand cocoons if you want to make yourself a regular-sized shirt (one pound of silk requiring between two thousand, and three thousand cocoons). With around seventy million pounds of raw silk produced every year, this requires nearly ten billion silkworm cocoons — a volume that has had a profound effect on the silkworm's nature. Having been bred in such huge numbers for years, silkworms are now entirely dependent upon humans for their survival.
Silkworms as food
Aside from making shirts and dresses, a silkworm's other main hobby is to be food for pet reptiles — and they're exceptionally good at that too. Bravo!
In fact, silkworms are so high in nutritional value that Chinese researchers considered using them as astronaut food in their space program. With the caterpillar's phenomenally high protein and amino acid content, scientists concluded that astronauts would only need to eat 170 of them a day (the equivalent of about a single silk sock) in order to get all the nutrients they needed. This means that even if your pet chameleon has absolutely no interest in joining the space program, it's going to find silkworms an incredibly valuable and easy source of nutrition.
The data
| Feeder Type | Fat | Calcium | Fiber | Protein |
|---|---|---|---|---|
| Silkworm | 10.6% | .34% | 5.95% | 63.8% |
| Cricket | 22.7% | 0.08% | 3.2% | 11.4% |
| Mealworm | 12.7% | 0.08% | 1.7% | 20.3% |
| Waxworm | 22.2% | 0.11% | 7.69% | 15.5% |
| Butterworm | 5.2% | 0.11% | - | 16.2% |
What is clear is that silkworms have an incredibly high protein content relative to other feeders. Not only does this make them exceptionally good reptile food, but should your pet iguana suffer any kind of injury, a silkworm's high protein content will promote faster healing. What's more, with a higher calcium content than most other feeders, silkworms are particularly good for gravid females, helping the production of healthy, fertile eggs. When you add the silkworm's low-fat content to the equation and the fact that they don't have sharp jaws or spiny legs that might hurt your beloved reptile, we start to see how silkworms are an ideal choice for your pet.
How to keep silkworms
What makes silkworms especially attractive to reptile owners is that they are remarkably easy to take care of. They can survive almost a week without food (if you forget to feed them) and will live up to a month before they cocoon. The only areas that need any real attention are temperature and dryness. For the best results, silkworms should be kept between 78° and 88° F, and in a moisture-free environment. Dryness is particularly important as condensation or damp food remnants can be a breeding ground for molds and bacteria that might damage your worms. That said, a simple plastic container should serve as an ideal home, provided there are plenty of holes punched in the lid so the worms can breathe and any condensation in the container can dry out.
So what do silkworms eat? The normal diet for your worms will be either mulberry leaves or store-bought silkworm food. Store-bought food is increasingly popular among reptile owners as mulberry leaves aren't always readily available, and the only real difference store-bought food makes to the silkworm is the quality of the silk in its cocoon. Either way, what's especially convenient about a silkworm's dietary habits is that the worm will only grow as much as you feed it. By restricting the worm's intake you can grow stable, healthy worms of any size you like (up to a maximum of about three inches). This is particularly useful if you own younger, smaller reptiles, and need to supply them with more conveniently-sized meals.
Under normal conditions though, a silkworm will grow from an egg to approximately one inch in length in about twelve days — and up to three inches in length in just under a month. At that point, the worm will start to cocoon and you'll have to decide whether you want to feed it to your pet or start weaving yourself a silk scarf.
The silky conclusion
When it comes to providing a tasty and nutritious meal for your pet reptiles, silkworms are about as nutritional as it gets. That said, as with all food, variety is the spice of life and a necessity also. Silkworms may be a great choice as a staple feeder, and while they can quite safely be used as the bulk of your reptile's diet, they shouldn't be used on their own. Even if your pet chameleon does finally make it into Low Earth Orbit, make sure it gets a wide and varied diet while it's up there.