Grizzled Mantis Caresheet
The Grizzled Mantis (Gonatista grisea) should be kept in an enclosure that is at least 3 times as tall as the mantis is long, and at least 2 times as wide as the mantis is long. Adult females can grow up to 2 inches long, while males are usually closer to 1.5 inches long as an adult.
The enclosure must have adequate ventilation, and can be solid glass/plastic or a mesh cage, but enclosures with glass or clear plastic sides and a mesh or screen top are ideal, due to the humidity requirements of this species. In any case, there must be some kind of material on the ceiling of the enclosure so the mantis can hang upside down during molting, as well as an empty space at the top which is at least 2 times the size of the mantis.
Grizzled mantises do well in living vivariums with live plants and microfauna (e.g., springtails and isopods) who will act as a sort of "clean up crew" by breaking down the mantis's waste and food scraps, thereby reducing the build up of mold and bacteria that can make your mantis sick or even die. You can certainly keep them in temporary enclosures such as mesh cages with silk plants (such as a leafy branch or ivy branch) and an easily disposable substrate such as sphagnum moss, or even just a paper towel. However, if you chose this approach you must be diligent about cleaning the enclosure and replacing the substrate at least once a week, because the humid conditions required for this species will promote the growth of mold and dangerous bacteria without a healthy population of microfauna to help keep it in check.
Temperature & Humidity
Grizzled mantises are native to the southern US, mainly Florida. These mantises are rarely seen in nature due to their excellent camouflage. The ideal temperature for them is 80°F to 85°F, but they can tolerate a range between 70°F and 90°F. They prefer higher humidity environments (70% RH and above as adults), but can handle somewhat lower humidity levels than that, if necessary. As nymphs, you must be careful to mist their enclosures very lightly, with a very fine mist. Since they have such short legs, and like to rest flat against surfaces, they can easily drown in a drop of water when young. Therefore, you must also make sure the substrate stays moist but not sopping wet, and that no puddles are allowed to form on the bottom of the enclosure.
Depending on the amount of ventilation, the enclosure should be given a light misting once a day. Grizzled mantises kept in mesh or screen cages should have their enclosures misted at least twice a day to maintain adequate humidity. Not only that, but misting the enclosure also allows the mantis to drink. Most mantises do not like getting sprayed directly, so it is best to try and spray around the mantis, but if you get them a little wet by accident, it is usually no big deal. Use spring water, distilled water, or water filtered by reverse osmosis (RO), but do not use plain tap water.
These mantises rely on their incredible camouflage to surprise their unsuspecting victims, and so they prefer more active prey that will "come to them", rather than ground-dwelling insects that they would have to seek out.