The Frog Blog

The Frog Blog

Saturday, 28 June 2014

Pet Spotlight: Silk Worms

Pet Spotlight: Silk Worms

Disclaimer: As with the Wintermelon post, I do not claim to be an expert in insects, breeding, feeders, or pets. All opinions expressed and experiences shared are my own and from what I read on the internet.

I bought three silkworms from a pet store on about Thursday 29th May. Normally silkworms are used as feeders for reptiles and, although I'm the owner of a considerable menagerie, these little ones were not for that purpose. I wanted to see them spin their cocoons and become moths.

Plus, they're really cute.

Some people may find them a bit gross, as they do with a lot of creepy crawlies. But I find them adorable. They have little feet for feeling on the front part of their bodies and suction feet from about 1/4 of the way onward. They have little buttocks that can clamp onto leaf stalks, too! Which makes removing them from their box a little tricky. You need to be firm and yet be careful not to a) squish them and b) break their legs. When they crawl on your skin, it's a little itchy, a bit like someone dragging a floor brush along your arm.

So aside from (lightly) squeezing them (they're sooo squishy!) and petting them, I got a plastic see-through box for them and threw in a bunch of washed white mulberry leaves, and let them get on with it. Silkworms eat voraciously, hence my new nickname for my trio: "Om nom noms". Just keep throwing mulberry leaves at them, but make sure they're fresh, because silkworms don't drink. They get all their hydration from the water in the leaves, and face it, dry leaves aren't exactly the most delectable. Clean out the faeces -- these guys poop as fast as they eat -- every so often.

I had them for two to three days before they just stopped eating altogether. Then they started spinning silk. Initially they were pretty lethargic, nibbling on the mulberry leaf a little, before just lying there again. I began to worry, as I'd never had silkworms before and was thinking, "Oh God, I can't even keep three worms alive?!"

Turns out they were ready to become cocoons. Overnight, two of them spun an opaque cocoon. A third was still spinning it the next morning when I came downstairs. I could still see its little head weaving back and forth as the cocoon thickened, and by mid-afternoon it, too, was out of sight in its little ball.

The interwebs say they take about three weeks to become moths, but it may be because it's horrendously hot where I am right now (35C on a normal day), they came out of their cocoons on June 10th -- well, two of them did. One was still inside its cocoon. As they (apparently) come out at dawn, I figured the remaining one wouldn't arrive until the next day, and I was right. I cleared out most of the faeces from before they became cocoons and the dried leaf that stayed with them for the 11-day-long cocoon period.

As I was also told by the internet, they sprayed a red liquid when they came out of the cocoon. So I cleared that out too. The first two that emerged look like females -- pretty big and wide, white, looks like the females on the internet. I hoped the third would be a male, otherwise these three will die within a week without laying eggs and I'll have to get new silkwormies.

Although considering they took a third of the time to become moths, perhaps they'll take a third of the time to die...

So it turned out the third one was, indeed, a male. Admittedly I couldn't tell the difference. He was the same size as the other two and more or less the same colour, perhaps with darker antennae. But when I came down the next morning, he had his butt jammed into a female's butt, so I guess he's a male?

I think the male is the left one in the left picture. You can also see the cocoon from which one of them emerged.

And although I'm rather quizzical about the timing of the event and its duration, it seems like the other female is already laying eggs -- considering adult moths neither urinate nor defecate, what else could these yellow things be? Our male could be more promiscuous and quick than I took him for...

For a couple of days, they mated, laid eggs, rinse and repeat. The male kept getting his wings and body caught in the silk so it was tough getting him out; the silk was tough and his body rather fragile. I ripped his wings a couple of times but his body was relatively intact, although he was still rather silky.

They managed to mate about three times in total (so one female participated twice) and there was a shedload of eggs.

I read on the internet that eggs will turn grey/black if they have been fertilised. So I left them where they are. Sadly -- but as expected -- the three adults died on 15th and 17th of June.

On about 16th June, some of the eggs did indeed turn grey/black (L), contrast with those that were unfertilised (R). Because my silk moths laid their eggs in two different places, I took half of the eggs -- still attached to the paper towel they were laid on -- and put it in a plastic tub, much like those takeaway microwaveable containers. Then I stuck the plastic container in a plastic bag, tied it, and refrigerated it. These should theoretically stay "fresh" for up to five years. They're my back-up silkworms. I don't fancy hatching hundreds of silkworms just yet -- can you imagine how much mulberry leaves they'll go through in a day!?

A couple of days later, the ones that were not refrigerated hatched.

Notice the little wriggly black things -- those are the baby silkworms. The hatched remnants of the eggs are grey and on close inspection, they have a hole in each of the sides.

I let the silk worm babies migrate of their own accord. Using small mulberry leaves -- as new as I can get, because their digestive tracts are still delicate and may not be able to digest larger leaves -- I placed new leaves on top and let them climb on. Eventually, after about two days, I'd moved most of them to a new container, cleaned the pink one, and replaced them.

A few of the babies got caught in the silk and couldn't move out. Others just died without apparent reason. I think I hatched about 200 worms and lost 10-20 initially.

Empty silkworm eggs
Well, currently the babies are still chomping away at the leaves. The leaves dry out quickly, so I have to keep replenishing them. I think I've lost another 20 in the past few days -- they're just little black hairs at the bottom of the plastic tub that don't move, so I assume they've gone.

If I feed them daily, they'll reach full cocoon-able state within a month, so let's see where we go from there. I hope they survive this baby stage and start to shed. If all things go well, some will be kept behind for breeding but most of the rest will end up as feeders for my lizards and amphibians.

I'll update with a later post. Until then, the silkworm babies say bye!


  1. it makes me feel guilty for buying silk ties!

    1. Aww. I'm guilty of a few silk ties and dresses, too! Considering they have to be boiled alive whilst in the cocoon (otherwise the enzyme they use to dissolve their way out ruins the silk) just so the silk cam be harvested... Yeah. Not buying anything silky again if I can help it :/

  2. I was just thinking (until I saw the other comments - hiya Glyn!) that you'd just make scarves for everyone. Except your gifts would take a few months.

    Here, I made you a scarf. From scratch. Fer realz.

    So you're a granny now? ;)

    1. My gifts would take a few months and a few thousand cocoons -- I don't think I can bear to boil my baby-in-a-cocoons alive in a bowl O.O

      LOL. Why would you say that ('granny')?!?!