Raising Silkworms at Home: A Practical Keeper's Guide

I've raised silkworms both as a soft feeder for my reptiles and just for the quiet satisfaction of watching the full cycle from pinhead egg to spun cocoon. They're one of the most rewarding feeders to keep — gentle, clean-eating, and genuinely nutritious — but they're also fussier about hygiene than a roach colony. Get the moisture and cleanliness right and the rest is easy.

Silkworms are the larvae of the domestic silk moth, Bombyx mori, a species so thoroughly domesticated it no longer exists in the wild. Everything below assumes Bombyx mori, which is what you'll get from any feeder supplier. (A few keepers raise Samia ricini, the castor-eating eri silkworm, but it's uncommon for home feeding and not what this guide covers.)

The life cycle, stage by stage

Knowing the cycle tells you what your worms need at any moment:

• ◆Egg (7-14 days): Tiny gray-to-yellow eggs the size of a pinhead. They hatch fastest held warm and stable, around 78-86°F. Many keepers buy eggs and warm them to trigger a synchronized hatch.
• ◆Larva (~3-5 weeks): The feeding stage and the only one that matters for feeders. The worms molt through five instars, eating constantly and growing from a 2 mm speck to a plump 3-inch caterpillar.
• ◆Pupa / cocoon (spins in 2-3 days): When a worm stops eating, wanders, and turns slightly translucent, it's ready to spin. Each cocoon is a single continuous silk thread that can run hundreds of meters long.
• ◆Adult moth (emerges ~2-3 weeks after spinning): The moths don't eat and barely move — they exist only to mate and lay eggs, then die. If you want silk or feeders rather than the next generation, you harvest cocoons before moths emerge.

If you're keeping them purely as feeders, you'll spend nearly all your time in the larval stage and rarely let them reach moth.

What you need to get started

Silkworms aren't demanding on gear:

• ◆A ventilated container — a plastic shoebox tub, deli cups, or a mesh-lidded bin. Air holes are essential to prevent the trapped humidity that breeds mold.
• ◆Paper towel or fine mesh liner for the floor, so you can lift out frass and old food cleanly.
• ◆A reliable food source — fresh mulberry leaves or commercial silkworm chow (more below).
• ◆A thermometer/hygrometer — silkworms care about their climate.
• ◆A soft brush or your clean fingers for moving worms. They're fragile; never pinch or drop them.
• ◆Egg cartons or cardboard tubes for spinning structure, if you're letting any reach cocoon stage.

I keep the whole setup in a warm, draft-free corner with indirect light. Direct sun cooks a small container fast.

Feeding: mulberry vs. chow

This is the make-or-break topic. Bombyx mori eat mulberry leaves and essentially nothing else — it's the one food their digestive system is built for. No mulberry tree nearby? You have two realistic options:

1. ◆Fresh mulberry leaves. The gold standard. Use only pesticide-free leaves, store extras wrapped in a damp paper towel in the fridge, and chop them small for the youngest worms. Wilted or moldy leaves cause disease, so refresh often.
2. ◆Commercial silkworm chow. A mulberry-based powder you mix with water and steam or spread into the bin. This is how most keepers raise silkworms year-round, especially out of mulberry season, and it's reliable and clean. It's not a compromise — it's the standard.

Feed at least twice a day, give young worms tender leaves cut small, and remove uneaten food before it wilts or molds. Worms eat ravenously in later instars; a big colony can plow through leaves shockingly fast right before spinning.

If you'd rather buy worms already at feeder size than start from eggs, you can order them from All Angles Creatures' silkworm collection.

Climate: temperature, humidity, light

• ◆Temperature: Aim for 78-85°F. Up to ~86°F speeds growth; below ~70°F slows them and invites disease. A low heat mat or a warm room spot does the job.
• ◆Humidity: Moderate — roughly 50-70%. Too dry and they fail to molt; too wet and you grow mold and bacteria. I'd rather err slightly dry and clean than damp.
• ◆Light: Indirect light only. Direct sunlight overheats the container and stresses the worms.

The balance to internalize: silkworms like it warm and a little humid, but their enclosure must stay clean and well-aired. Warm + wet + dirty is exactly the combination that wipes out a colony.

Hygiene is the whole game

Silkworms are famously disease-prone, and almost every silkworm die-off I've seen or heard about traces back to hygiene. The classic killers are well documented in sericulture literature — flacherie (bacterial/viral gut disease, usually from spoiled food and heat), grasserie (a viral disease), and muscardine (a fungal infection). The FAO's manuals on silkworm rearing and sericulture treat clean rearing as the primary disease-control tool, and that matches my experience exactly.

My routine:

• ◆Wash hands before and after handling. You are the main vector for disease into the bin.
• ◆Remove frass and old food daily. A mesh or paper liner makes this a 30-second lift-and-replace.
• ◆Keep the bedding dry. Condensation on the walls means cut back moisture and add ventilation.
• ◆Don't overcrowd. Crowded, competing worms stress and spread disease. Spread them out or split into a second tub as they grow.
• ◆Quarantine sick worms. Lethargy, discoloration, shrinking, or refusing to eat are red flags — pull those worms immediately before they infect the rest.

Why silkworms are a strong feeder

For reptile and amphibian keepers, silkworms punch above their weight nutritionally. They're soft-bodied with very little chitin, so they're easy to digest and gentle on animals recovering from illness or with impaction risk. Importantly, they have a better calcium-to-phosphorus ratio than most feeders — crickets, mealworms, and roaches are all phosphorus-heavy, while silkworms come closer to balance. That said, "closer to balance" isn't "complete," so I still dust with calcium for growing reptiles and egg-laying females, where calcium demand is highest and metabolic bone disease is the risk. They're a favorite of bearded dragons, leopard geckos, chameleons, and many frogs.

If you want to harvest silk

Should you let some reach cocoon, you can reel real silk. Collect firm, undamaged cocoons before the moths emerge (an emerging moth breaks the single continuous thread). Gently boil or steam the cocoons to soften the sericin, the natural glue binding the fibers, then find the loose end and unwind. It's delicate, slow work, but watching a few hundred meters of thread come off one cocoon is genuinely remarkable. Store finished silk dry and cool to prevent tangling.

Most feeder keepers skip this and simply feed worms off before they spin — but the option is a nice bonus of the species.

My quick-start summary

Keep them at 78-85°F, feed mulberry or quality chow at least twice daily, remove waste every day, keep the bin dry and uncrowded, wash your hands, and dust with calcium before feeding to growing reptiles. Do those six things and silkworms are one of the easiest, cleanest, most rewarding feeders you can raise.

For another soft, high-moisture feeder option, see my guide on hornworms, or browse all my feeder and exotic care guides.