Praying mantises eat live insects exclusively. The rule that governs every feeding decision: prey length must never exceed the mantis’s own body length (not counting wings). Break that rule and you risk injury; follow it and feeding becomes one of the most satisfying parts of keeping these animals.
This guide covers what to offer at each instar, how often to feed, gut-loading, dangerous foods, and the pre-molt fast. It applies to Sphodromantis viridis, Tenodera sinensis, and Hierodula spp. unless otherwise noted.
For housing and enclosure setup, see the praying mantis care guide.
Key Takeaways
- Mantises are visual predators. They only strike moving prey. Dead insects will be ignored.
- The size rule: prey length is no more than mantis body length (measure head to abdomen tip, not counting wings).
- Juveniles (L1-L4) eat every 1-2 days; adults eat every 2-3 days, or until they refuse.
- Fruit flies (Drosophila melanogaster) are the only safe prey for L1-L2 nymphs.
- Gut-load all feeders with leafy greens, carrot, or bee pollen for 24 hours before offering them.
- Fireflies are lethal: even one firefly can kill a mantis within hours due to lucibufagin toxins.
- A mantis that refuses food, darkens in colour, and hangs motionless is in pre-molt. Remove all prey immediately and do not disturb it for 7-10 days.
- Never feed for 24 hours after a molt. The new exoskeleton is still soft.
What do praying mantises eat?
Praying mantises eat live insects in captivity. Offer prey no longer than the mantis’s body length, measured head to abdomen tip. For early instars, aim for prey half that length. Start L1 nymphs on flightless Drosophila melanogaster, move to larger flies and crickets as they grow, and offer food every 1-3 days depending on age.
Why mantises only eat live prey
Mantises are ambush predators that hunt by visual tracking. Their compound eyes detect prey movement from up to 20 cm away. Once something stops moving, interest disappears.
- Dead or freeze-dried insects will not trigger a strike. A few experienced keepers train adults to take dead prey from tongs, but don’t count on it.
- Prey must be active but not so large it fights back. An oversized cricket can chew through a mantis’s leg or eye. Thrashing prey injures nymphs during the grapple.
- Every meal is a hunt. The mantis locks on, sways to judge distance, and strikes with its raptorial forelegs in under 1/30th of a second.
Prey options by instar
The table below covers the most commonly kept beginner species. “Prey length” means the feeder insect from head to tail. Match this to the mantis’s current body length using the size rule above.
| Instar | Mantis body length | Best prey | Prey length | Frequency |
|---|---|---|---|---|
| L1 (hatchling) | 5-8 mm | Drosophila melanogaster (flightless) | 1-2 mm | Daily |
| L2 | 8-12 mm | D. melanogaster, springtails | 1-3 mm | Daily |
| L3 | 12-18 mm | D. hydei (flightless), micro crickets | 3-5 mm | Every 1-2 days |
| L4 | 18-25 mm | D. hydei, small waxworms, house flies | 4-8 mm | Every 1-2 days |
| L5-L6 | 25-40 mm | House flies, small crickets, small dubia nymphs | 8-15 mm | Every 2 days |
| L7-L8 (sub-adult) | 40-60 mm | Crickets, blue-bottle flies, medium dubia | 15-25 mm | Every 2 days |
| Adult | 60-100+ mm | Crickets, blue-bottle flies, dubia roaches, locusts | Up to body length | Every 2-3 days |
Notes:
- L1 nymphs require melanogaster fruit flies. Nothing else is consistently small enough. Buy a flightless culture before your oothecae hatches. See the fruit fly culture setup guide to get one going before hatch day.
- Hydei flies (D. hydei) are roughly 3x the size of melanogaster: the go-to feeder from L3 through early L5.
- Blue-bottle flies move fast and trigger aggressive strikes: excellent from L6 onward.
- Dubia roaches have the best nutritional profile: high protein, low fat, more calcium than crickets, soft enough not to injure your mantis.
For species-specific prey schedules, see the Sphodromantis viridis care guide and the Tenodera sinensis care guide.
The size rule, explained
The most common beginner mistake is offering prey that is too large. A 4 cm mantis does not need an adult cricket. An adult cricket is 2.5-3 cm and can injure a 4 cm mantis if the grapple goes wrong.
How to apply the rule:
- Measure your mantis: head to abdomen tip, ignoring wings.
- Choose prey shorter than that measurement. Start at 75% of body length; go to 100% only for healthy adults with intact grasping legs.
- Watch the first 60 seconds. If the mantis drops the prey immediately, or the prey crawls over the mantis unchallenged, it’s too large. Go smaller.
- Never offer more than one prey item at a time: a free insect can injure a mantis that is eating.
After every molt, drop back one prey size. The new exoskeleton is soft for 24-48 hours.
How often to feed
Feeding frequency shifts as mantises grow. Young nymphs have fast metabolisms and need daily feeding; adults slow down considerably and only need food every 2-3 days.
A practical approach: offer food every other day and watch what happens. A mantis that strikes within 60 seconds was hungry. One that walks away or tracks but doesn’t commit is full or pre-molt. Remove the prey and try tomorrow.
Remove uneaten prey within 24 hours. A live cricket left overnight can harass and injure a resting mantis. I have seen one chew through a mantis’s femur while it slept.
Gut-loading your feeders
A mantis fed nothing but nutritionally hollow crickets that have been living on cardboard will gradually decline. Gut-loading (feeding your feeder insects something nutritious 24-48 hours before offering them) transfers those nutrients directly to your mantis.
What to gut-load with:
- Dark leafy greens (collard greens, dandelion leaves, kale): calcium and carotenoids
- Carrot or sweet potato: beta-carotene and vitamin A
- Bee pollen: protein and B vitamins
- Commercial cricket gut-load powder: convenient and calibrated
What not to gut-load with:
- Iceberg lettuce (no nutritional value)
- Citrus fruit (acidic, stresses insects)
- Spinach (high oxalates bind calcium)
For crickets: place them in a clean container with gut-load food 24 hours before feeding, then remove frass. Dubia roaches kept on carrot and dry oats are perpetually gut-loaded. For fruit flies: shake some into a small container with mashed banana or bee pollen the night before.
Calcium dusting is worth doing for adult females producing oothecae. Dust prey lightly once every 2 weeks with calcium powder (no vitamin D3).
Foods NOT to feed your mantis
Some insects are outright dangerous. Others carry risks that aren’t obvious.
| Prey type | Why to avoid |
|---|---|
| Fireflies (Lampyridae) | Contain lucibufagins: lethal cardiotoxins. Even one firefly can kill a mantis within hours. |
| Wild-caught insects | Unknown pesticide exposure, parasites, and pathogens. Never feed insects from your garden or outside. |
| Bees and wasps | Capable of stinging before being consumed; can seriously injure or kill a mantis. |
| Ants | Formic acid causes chemical burns; they also bite aggressively in numbers. |
| Black soldier fly larvae (BSFL) | Several reports of BSFL killing mantises; mechanism unclear, possibly a digestive enzyme interaction. |
| Mealworms | Hard chitin head capsule is a choking and impaction risk for nymphs. Occasional use only for adults. |
| Spiders | Will bite back. Not worth the injury risk when safe alternatives exist. |
| Dead or freeze-dried insects | Will not be recognized as prey by most mantises; a rotting carcass also contaminates the enclosure. |
Fireflies and wild-caught insects are the two absolute non-negotiables. Everything else on the list carries lower but real risk. Avoid them when captive-bred feeders are available.
Water: how mantises drink
Mantises do not drink from a bowl. They lap droplets from enclosure walls and leaves, a behaviour you need to accommodate by misting.
Mist one side of the enclosure wall lightly every 2-3 days for most beginner species. You will often see the mantis move to the wet wall and drink within minutes. For Hierodula and higher-humidity species, mist every 1-2 days.
Do not spray the mantis directly. Cold water causes stress. Do not soak the substrate. Mist the walls only, so the surface dries within an hour.
Fasting before a molt: what to expect and what to do
The most stressful moment in mantis keeping for new owners is when a mantis simply stops eating. In most cases, this is normal: it means a molt is coming.
Pre-molt signs:
- Refuses food for 3-7 days (sometimes up to 10 days for adults)
- Colour darkens slightly: a green mantis may look olive-grey
- Hangs motionless from the mesh lid or a branch for hours
- Abdomen looks shorter and fatter than usual (the new exoskeleton forming underneath)
- May drink water but ignore food entirely
What to do when you see these signs:
- Remove all prey from the enclosure immediately. A live cricket is the most dangerous object in the enclosure when a mantis is mid-molt.
- Mist the walls lightly to bring humidity to the upper end of the species range.
- Do not handle the mantis, do not tap the enclosure, and do not move it.
- Do not attempt to feed again until at least 24 hours after the molt completes, preferably 48 hours. The new exoskeleton is still hardening.
- When you do resume feeding, start with prey at the smaller end of the size range.
A mantis that fasts 7-10 days then eats normally after molting is not sick. That is a healthy molt cycle. The mantis molting guide covers every warning sign and failure scenario.
Prey refusal: when to be concerned vs. when to wait
Not every feeding refusal means a molt is coming. Here is how to read the situation.
Probably fine: wait and try again in 1-2 days:
- Mantis is in confirmed pre-molt (hangs motionless, abdomen looks thick)
- Mantis molted within the last 48 hours
- Room temperature dropped below 20 °C. Mantises slow their metabolism significantly in cool conditions.
- Mantis is an adult female that has recently laid an oothecae. Egg production is energetically expensive and she may rest for 1-2 weeks afterward.
Worth investigating:
- Refused food for more than 14 days with no pre-molt signs
- Abdomen narrow and pinched (visible weight loss)
- Lethargy despite correct temperatures
- Missing or malformed legs making prey capture difficult
Check temperature first. A mantis at 18 °C barely moves or eats. Raise it to 24-26 °C and offer prey 24 hours later.
Feeding after a molt
A freshly molted mantis may look pale, sometimes almost white, before the new exoskeleton hardens over 4-12 hours. Wait at least 24 hours before offering any prey (48 for adults). Offer prey one size smaller than before the molt. Watch the full interaction. If the mantis fumbles prey it normally catches easily, remove it and wait another day. Do not handle for at least 5 days.
Not eating for a day or two post-molt is normal. They just shed their entire exoskeleton. Rest is expected.
Putting it all together
A healthy adult Sphodromantis viridis or Tenodera sinensis routine in one place:
- Every 2-3 days: one prey item at 70-100% of body length: cricket, dubia roach, or blue-bottle fly
- 60-second rule: strike within a minute means hungry; no reaction means remove and try tomorrow
- Every 2 weeks: dust feeders lightly with calcium powder
- Pre-molt (7-10 days before): fast completely, remove all prey
- Post-molt: wait 48 hours, then offer prey one size smaller than usual
- Year-round: mist enclosure walls every 2-3 days so the mantis can drink
Adjust prey size up after every molt. Adjust frequency down as your mantis ages.
FAQ
What do praying mantises eat as pets? Pet praying mantises eat live insects only. Fruit flies for L1-L2 nymphs, house flies and small crickets from L3-L6, and crickets, dubia roaches, or blue-bottle flies for sub-adults and adults. Prey size should never exceed the mantis’s own body length.
How often should I feed my praying mantis? Feed L1-L4 nymphs daily or every other day. Feed L5 through adult mantises every 2-3 days. Adult females producing oothecae may eat daily. When a mantis refuses food three times in a row with no pre-molt signs, check temperature before assuming illness.
Can praying mantises eat crickets? Yes, crickets are a fine staple for sub-adults and adults. Choose crickets no longer than the mantis’s body length. Always gut-load crickets for 24 hours before offering them, and never leave a live cricket alone with a mantis overnight. Crickets bite.
What should I never feed a praying mantis? Never feed fireflies (lucibufagin toxins are lethal), wild-caught insects (pesticide risk), bees or wasps (can sting before being eaten), or ants (formic acid burns). Avoid black soldier fly larvae and mealworms for nymphs. Dead insects are safe but will be ignored by almost every mantis.
How do I know if my mantis is hungry or about to molt? A hungry mantis is alert, tracks movement, and strikes quickly when prey is offered. A pre-molt mantis refuses food, hangs motionless from the mesh ceiling, and may look slightly darker than usual. Pre-molt can last 7-10 days. Remove all prey the moment you see those signs.
Do praying mantises need water? Yes. Mist one wall of the enclosure every 2-3 days. Mantises drink by lapping droplets from surfaces. Do not use a water dish and never spray the mantis directly. Most beginner species do well at 50-60% relative humidity maintained by wall misting.
Go deeper
- New to mantises entirely? See the praying mantis care guide for housing, temperature, humidity, and choosing a first species.
- Keeping an African mantis? The Sphodromantis viridis care guide has species-specific prey schedule and molting timeline.
- Keeping a Chinese mantis? The Tenodera sinensis care guide covers prey size for a larger mantis.
- Mantis about to molt? The praying mantis molting guide covers every pre-molt warning sign, mismolt recovery, and what normal looks like hour by hour.
- Need feeder insects? The best mantis enclosures guide has our setup picks, and the fruit fly culture setup gets your L1 food source sorted before hatch day.
Have a mantis that’s been refusing food for three weeks with no molt sign? For anything that might be a health issue, an invertebrate-experienced exotic vet is always worth consulting. They exist in more cities than you’d think.