Praying mantises eat live insects, and the right prey depends almost entirely on the mantis’s size. A tiny newborn nymph needs fruit flies, while a full-grown adult can take down adult crickets, roaches, and bluebottle flies. Getting the size match right is the single most important part of feeding a pet mantis.
Matching Prey Size to Your Mantis
Mantises are ambush predators that grab prey with their forelegs, so the food item needs to be small enough for them to catch and hold. A good rule of thumb: the feeder insect should be no longer than the mantis’s body, excluding the wings. Offering something too large risks injury to the mantis. Something too small may not trigger a feeding response at all.
For the earliest life stages (first and second instar nymphs, freshly hatched and very small), fruit flies are the go-to feeder. Wingless or flightless fruit flies work best because they’re easy for tiny nymphs to catch. Aphids, gnats, and pinhead crickets also work at this stage. Offer one to three fruit flies daily or every other day.
By the third instar, your mantis is big enough to start eating houseflies, small crickets, and small roaches. From this point through the later nymph stages, you can feed every one to three days, gradually increasing the size of the prey as the mantis grows through each molt. By the time it reaches adulthood (typically the seventh or eighth instar for many species), it can handle adult crickets, bluebottle flies, and full-sized roaches.
Best Feeder Insects for Captive Mantises
Variety matters. A mantis that eats only one type of prey may miss out on certain nutrients, so rotating between a few feeder species is ideal. The most commonly used options include:
- Fruit flies: Perfect for nymphs. Available in flightless cultures from most pet supply stores.
- Blue bottle flies: A favorite for medium to large mantises. They’re active enough to trigger a hunting response.
- Crickets: Widely available and affordable, though they should be appropriately sized. Remove uneaten crickets from the enclosure, as they can nibble on a molting mantis.
- Dubia roaches: Nutritious, easy to keep, and less likely to bite your mantis than crickets.
- Grasshoppers and moths: Good supplemental prey for larger mantises, adding variety to the diet.
Foods to Avoid
Not every insect is safe. Black soldier fly larvae have been reported to kill mantises, likely due to digestive issues, since mantises break down food internally in their stomachs rather than externally like spiders. Bees and wasps can sting your mantis before being eaten. Spiders can bite back. Earthworms and slugs are also poor choices because their slime can cause problems.
Crickets deserve a small caution too. While they’re a staple feeder, crickets that are too large or left loose in the enclosure overnight can stress or injure a mantis, especially during a molt when the mantis is soft and vulnerable.
Wild-Caught Insects: Worth the Risk?
Feeding your mantis insects you catch outside is tempting, especially since it mimics their natural diet. It can work, but it carries real risks. Pesticides are the biggest concern. In suburban and urban areas, insects regularly come into contact with herbicides and insecticides. Your mantis eats the whole insect, toxins included.
Parasites are the second issue. Wild insects can carry nematodes (including horsehair worms), mites, and various bacterial infections. Captive-bred feeder insects from a reputable supplier eliminate both of these risks. If you do feed wild-caught prey, stick to insects from areas you know haven’t been sprayed, and avoid anything collected near treated lawns, gardens, or agricultural fields.
Water and Humidity
Mantises don’t drink from a water dish. They lick droplets off the walls of their enclosure and off plants, so misting is the primary way to keep them hydrated. Use spring water, distilled water, or reverse osmosis filtered water. Tap water can contain chlorine and minerals that aren’t ideal.
How often you mist depends on the enclosure type. Mesh or screen cages dry out fast and need misting once a day, or twice during hot summer weather. Glass or acrylic enclosures hold humidity longer, so every two to three days is usually enough. When you mist, spray around the mantis rather than directly on it. Most mantises don’t appreciate being sprayed and may react with stress.
Honey as a Supplement
A small drop of honey can serve as an emergency energy boost for a mantis that seems lethargic, is refusing food, or has been vomiting. You can offer it on the tip of a toothpick or a small stick, placing it near the mantis’s mouthparts. Some keepers offer honey once or twice a week as a treat, but it’s a supplement, not a replacement for live prey. A healthy mantis eating on a regular schedule doesn’t need it.
How to Tell If Your Mantis Is Full
The easiest visual indicator is the abdomen. A well-fed mantis has a plump, rounded abdomen. A mantis that needs food will have a noticeably flat or concave abdomen when viewed from the side. You don’t need to feed on a rigid schedule. Instead, check the abdomen every day or two. If it looks thin, offer prey. If it’s still round from the last meal, wait.
Overfeeding is possible, particularly with adult females, who will eat as much as you offer. An overly distended abdomen can make movement difficult and, in rare cases, lead to rupture during a fall. For adults, feeding every two to three days and letting them skip a day between meals keeps them healthy without overdoing it. Nymphs that are actively growing can eat more frequently, since they need the energy to fuel their next molt.