So this article, obviously, will be about silk. The article is three parts. Part I is the introduction, I discuss the amazing insects that produce silk. Part II is the spider silk part, and part III is the bombyx mori silk or the natural silk.
There are few insect that produces silk and only two type of forest pest, defoliators and sawflies. The defoliator’s larval or caterpillar rise the moth, and the sawfly is the larvae of primitive group of wasps.
The silk is a proteinaceous liquid produced by glands inside the insect, when needed it is transferred to the spinneret by fine tubes, either to the head, where the silk worm spinneret is or to the end of the abdomen, where the spinneret is for spiders.
1- Mullbery Silk Worm
The scientific name is Bombyx Mori and it has been domesticated from its wild ancestor Bombyx Mandarina 2700 BC in China. The larva produces the well known silk fibers in form of cocoons, figure 1. We will discuss this in details in part 3.
2 – Spiders
Spider produce a very amazing silk, lighter and stronger than steel. It can take a very large amount of deformations without breaking. We will discuss spider silk in part II.
3 – Sawfly
Similarly to Bombyx Mori, the sawfly larva spin a reddish brown cocoons around the defenseless pupal stage in which they turn into adults, figure 3.
4 – Other Moths
The Gypsy moths are examples of moths that produce silk. After the Gypsy moths larva hatch, they disperse using a silk thread like a parachute to ride the strong wind. Their amazing anatomy (hair) with the silk thread help carry them for miles. Many other moths depend on this method of dispersing to spread.
Other moths leave a mark trail of silk threads to guide the new caterpillar from and to the nesting place.
Some larva use the silk to build a tent to protect from weather and predators, figure (7).
Other caterpillars use the leaves and the twigs to create a shelter, figure 8.
Although there are many insect in the forest to produce silk buy, unfortunately it is not economical to collect it. These insects are very hard to domesticate as well, including the spiders.
So as most of the authors of the references below advise, when you see these structures out in the wild, take a moment and admire their great construction and beauty.
- Douglas C. Allen, Insect-Produced Silk: From Textiles to Tents, The New York forest Owner. 37: 6, 1999.
- Khalil Moukayes, Tammam Al-Abed and Eman Okasha, The influence of Various Mounting Materials on Production of Silk Worm Bombyx Mori L., Teshreen University Journal for Studies and Scientific Research – Biological Science Series, Vol 28 (1), 2006. p133 – 143.
- Martha E. H. Rustad, Silkworms, Capstone Press, Mankato, 2009.
- Jason Plamer, Spider silk spun into violin strings, 5 March 2012, available from http://www.bbc.co.uk/news/science-environment-17232058.