Did you know that there are hundreds of types of silkworms? Depending on the breed, worms may vary in body length, feeding days, disease resistance or tolerance to temperature changes. In addition, the types of silk they produce will also differ by breed.

Existing breeds of silkworms

The types of silkworms can be grouped into four geographical categories:

  • European silkworms
  • Chinese
  • Japanese
  • Tropical

According to this geographical group, the different types of silkworms differ in the number of annual cycles. In this sense, they can be:

  • Monovoltine. They have only one cycle per year. They are the most common in the temperate climates of the European geographical group.
  • Bivoltine. In this case the worms have two annual cycles. They are found in subtropical regions of the Chinese and Japanese geographical groups. The disadvantage of bivoltine worms is that it is more difficult to know when they will hatch and that it may be more difficult to feed them in winter if there are no mulberry trees with leaves.
  • Polyvoltines. They have several annual cycles and belong to the tropical geographic group.

Some types of silkworms

To differentiate between all the silkworm breeds that exist is complicated (almost impossible if we take into account the crossings), since many of them are practically the same, being most of them of smooth white or zebra-shaped appearance. However, we also find very peculiar types of silkworms, such as:

  • Egyptian silkworms: black in color with beige stripes. The larvae are banded, the cocoons are light green and the eggs are not adherent.
  • L70: Japanese silkworms yellow zebra silkworms (with a light greenish tint).
  • T42: Japanese race, with yellow and zebra-like larvae.
  • W30: Another Japanese strain with very striking markings, reminiscent of a dragon, and brownish tones.
  • L11: Japanese variety with orange or reddish bands in some phases.
  • Classic Zebrados. One of the most common and resistant silkworm breeds, they are characterized by their whitish color and dark stripes. Their silk is yellow.

What is the season for silkworms?

Silkworms lay their eggs in the winter season, and hatch in the spring season, between March, April and May.

In order for the silkworms to develop properly in the egg and not die, it is important that the eggs are in a cold place, at rather low temperatures. If the temperature is high, they may think it is already spring, hatching prematurely and not forming as they should.

As a general rule, the hatching of the eggs is synchronized with the appearance of the first shoots of the mulberry trees. This occurs when temperatures rise and the days become longer.

Where do silkworms come from?

Silkworms, like any caterpillar, go through four basic stages of development: egg, larva, chrysalis, pupa and imago.

The eggs from which silkworms hatch are between 1 and 1.5 mm long. Their shell is a membrane of chitinous matter, ranging in color from light yellow to slate gray, with a purplish or greenish hue at the end. Eggs that have fertilized maintain their yellow color, and when they are about to hatch, is when the greenish tone appears.


If you enjoyed learning a little more about these fascinating animals, we invite you to read this other article on how silk is made. In this one we focus on the production of silk, from the eggs of silkworms, to the elaboration of our silk scarves.

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