The two rules
- Prey size ≤ 1/3 the mantis’s body length. Bigger prey = injuries.
- Frequency scales with stage. Young nymphs eat constantly; adults eat once every few days.
Everything else in this guide is detail.
Prey species by instar
L1–L2 nymphs
Melanogaster fruit flies (small wingless or flightless). Almost exclusively. L1 nymphs cannot subdue anything larger.
Source: a single fruit fly culture vial (~$8–10) feeds a single nymph for weeks. One culture produces a steady supply of flies for about 3–5 weeks before it exhausts its media and crashes. Start a fresh culture every 2–3 weeks so you always have flies coming online — see our fruit fly culture care guide for the full routine.
How to offer: tap a small cluster (5–10 flies) into the enclosure. Replenish every 1–2 days.
L3–L4 nymphs
Hydei fruit flies (larger). Same source ecosystem as Melanogasters, just a different culture. Some keepers stick with Melanogasters and just offer more — also fine.
Optional: small houseflies (1/4 inch) once the nymph hits L4.
How to offer: 4–6 flies per feeding, every 2 days.
L5–L6 nymphs
Houseflies and bottle flies. Cultured houseflies are the workhorse — order pupae from a feeder supplier such as blue or green bottle spikes, hatch them in a deli cup over a week. New to feeders? See our feeder insects guide.
How to offer: 2–3 flies per feeding, every 2–3 days.
L7+ / Adults
Bottle flies (blue, green), moths, optionally small crickets and dubia roaches — depending on species.
Some species (Orchid, Spiny Flower) refuse crawling prey at every life stage. Others (African Twig, Double Shield) eat everything. Check the relevant species care guide — Dead Leaf and Ghost each have their own quirks too.
How to offer: 1–2 prey items every 3–4 days.
Prey-to-mantis size ratio
| Mantis body length | Max prey body length |
|---|---|
| 0.5 cm (L1) | 0.2–0.25 cm (Melanogaster) |
| 1 cm (L2–L3) | 0.3 cm (Hydei) |
| 2 cm (L4) | 0.6 cm (small housefly) |
| 3 cm (L5) | 1 cm (housefly) |
| 5 cm (L6+) | 1.5 cm (bottle fly) |
| 7+ cm (adult) | 2 cm (large bottle fly, moth, cricket) |
Melanogaster fruit flies are the practical exception — at ~0.2–0.25 cm they sit at or just above the 1/3 line for L1 nymphs, but their soft bodies make them safe to handle anyway.
Err smaller. A too-small prey item is a non-event; a too-large one risks injury.
Feeding frequency
Generally:
- L1–L2: every 1–2 days (or “always” — keep flies in the enclosure)
- L3–L4: every 2 days
- L5–L6: every 2–3 days
- L7+ adults: every 3–4 days
- Premolt: zero. Stop feeding the moment you suspect premolt (our molting guide covers the signs).
- Post-molt: wait 24–48 hours before resuming feeding. The mantis is too soft to safely subdue prey. A soft, freshly molted mantis can also be injured by feeder insects walking on it — another reason to wait until the cuticle hardens and color returns.
- Gravid females: feed slightly more — every 2 days vs every 3.
Skip a feeding if the abdomen is round and full. Don’t skip if the abdomen is thin and concave.
Reading appetite
A healthy mantis with good appetite will:
- Track a flying prey item with the head as it moves
- Adopt a stalking posture (lowered, body tense, raptorial legs cocked)
- Strike within 30 seconds of getting in range
A mantis refusing food might be (for a full walkthrough, see why your mantis isn’t eating):
- In premolt (most common reason; fasting lasts roughly 2–7 days for nymphs — longer for later instars — and 1–2+ weeks for adults approaching the final molt)
- Recently fed (already-full abdomen; check from below)
- Receiving the wrong prey (Orchid offered a stationary cricket; Spiny Flower offered a slow-moving roach)
- Too cold (below 70°F, most species slow dramatically)
- Old (adult females in their final weeks often refuse food)
Gut-loading prey
For optimal nutrition, feed your feeder insects nutritious food for at least 24 hours before offering them to your mantis. This is “gut-loading.”
Fruit flies: standard culture media is sufficient (already enriched with yeast and nutrients).
Houseflies: feed pupae a sugar-water mix as they emerge. Calcium dusting is borrowed from reptile keeping and is largely unnecessary for mantises — well-gut-loaded flies are enough.
Crickets/dubia: feed them fresh greens, carrots, and high-quality cricket food for 24–48 hours pre-feed. Avoid spinach, citrus, or anything moldy.
How to dispense fruit flies without flooding your house
- Tap the bottom of the culture against a hard surface to knock flies down.
- Quickly invert the culture over the enclosure mouth.
- Tap a few flies in. Re-cap the culture.
- Use a small funnel or cup-with-vent if your aim is bad.
Loose flies in your kitchen are an inevitable cost of the hobby. Sealed cultures and fast hands minimize the damage.
Water
Mantises drink mist droplets off enclosure walls and perches. They rarely drink from standing water. A daily light mist on the walls (not the mantis itself) is sufficient hydration for almost all species.
The exception: very large adult mantises (Dead Leaf, Double Shield) may benefit from a shallow water dish if you observe them ignoring mist droplets. Keep any dish extremely shallow (a bottle cap) and add a pebble or sponge so the mantis can’t drown — most keepers skip the dish entirely and rely on misting.
What not to feed
- Wild-caught insects. Pesticide exposure is unpredictable and often fatal.
- Mealworms. Tough exoskeleton and hooked mandibles — risk of mantis injury.
- Spiders, ants, ladybugs, fireflies. Toxic or aggressive.
- Pinky mice. Inappropriate for mantises — skip entirely.
Stick to the prey species above and you’ll have no problems.