The eggs start out at tiny, yellow dots. By the time they get to you, they’ll probably be gray-green, gray-purple, or light brown. If you see a different color, you might have eggs with a rare mutation![3] X Trustworthy Source PubMed Central Journal archive from the U. S. National Institutes of Health Go to source The silkworm is a domesticated species that doesn’t exist in the wild. [4] X Research source If you see its wild relatives on mulberry trees in East Asia, leave them on the tree—they can’t be bred the same way. [5] X Research source
Careful—they like a warm room, but direct sunlight is too much heat. [7] X Research source The eggs don’t do well if they’re super dry or super moist. If the room is dry, try adding a little square of damp paper to the container, but not touching the eggs. If the container is damp enough that drops form on the sides, move it somewhere drier. [8] X Research source
It’s normal for some eggs to fail to hatch. Blue eggs that fail to hatch might be a sign that the eggs weren’t handled right, so try ordering from a different supplier next time. [11] X Research source (But some blue eggs can still hatch, so don’t give up them. )
This temperature is higher than the standard food-safe fridge temperature, so use a separate mini-fridge If your silk worm breed was labeled “bivoltine,” “polyvoltine,” or with a number 100 or above, you could try to breed multiple generations per year, between spring and fall. Even then, the breeding schedule isn’t guaranteed, since it’s affected by heat and light. [13] X Research source
Newly hatched silkworm larvae are tiny squiggles. If you hatched the eggs in a petri dish, you can catch the squiggles on the end of a fine tip paintbrush to move them. [16] X Research source It’s also fine to put the whole petri dish in the box. The larvae start out very small, so one container to start with is fine. If they start to get overcrowded as they grow, move some to a second container. Giving the silkworm larvae indirect sunlight during the day is nice if you can manage it. Silkworm larvae do react to light, and will feed more if they have light during the day and darkness at night. [17] X Research source That said, the silkworms won’t die if you keep them in the dark. [18] X Research source Just be careful not to put the container in direct sunlight, which can overheat them. [19] X Research source
If you can’t get the young leaves, use artificial food and switch to mature leaves later. Ask the people who sell the leaves whether good-quality leaves will be in season until at least 24 days after the eggs hatch. [21] X Research source If not, it’s better to use artificial food the whole time instead. Silkworms fed on mulberry leaves sometimes won’t accept artificial food later. [22] X Research source
It’s even better to go the extra mile and disinfect them. [26] X Research source To do this, add 3 tablespoons (44 mL) of bleach and a drop of dishwashing detergent to 1 gallon (3. 8 L) of water. Soak the leaves for three minutes, then rinse them very thoroughly under running water. (Any soap left can kill the larvae. ) Shake dry and store in plastic bags in the fridge.
For the first couple days, use a soft paintbrush to very gently pick up the tiny, newly hatched larvae and move them off of the old leaf, then onto the new one. [28] X Research source If the newly hatched larvae aren’t eating, the leaves might be too thick. Try slicing them as thinly as you can and sprinkling them into the container, or switch to artificial food. [29] X Research source
It’s best to leave the larvae alone while they molt. In each molt, they rest for about a day, staying still with their head held up before shedding their skin. [31] X Research source Let them snooze and come back to clean tomorrow! Don’t wash with water and especially not soap, which can kill the larvae. The life cycle is only a few weeks long, so you can wait until they’re in cocoons before you do a thorough clean.
If some of the silkworms have already started to spin silk, leave those ones alone. Interrupting the spinning can kill them. [34] X Research source
After two or three days of spinning, the silkworm inside spends another two or three days pupating. After this point, you can cut open the end of a cocoon with a razor blade, and gently pull out the pupa (for instance, to show them to a science class). If you are very careful and return the pupa to the cocoon, it can still become a moth. [36] X Research source The moths usually come out in the early morning, so start waking up early if you want to be there when it happens. [37] X Research source
Silkworm moths can’t fly, so you can take off the lid to look at them without much risk of them escaping. [42] X Research source
If you want to experiment, it’s usually more consistent to cross-breed in spring. If you can, separate the sexes so you can combine the males of one strain with the females of another. (The male larvae are usually bigger and can have different markings, but it’s hard to tell in some strains. [44] X Research source )
