Dietary variety is the key to success in rearing many herps and invertebrates. Unfortunately, options for newly-transformed frogs and salamanders, Poison Frogs and other small species and hatchling spiders are limited. A diet of fruit flies, springtails and pinhead crickets sometimes suffices, but as I learned when rearing the endangered Kihansi Spray Toad, other foods are often necessary. Praying Mantid Egg cases (properly termed “oothecum”), which may be collected or ordered from commercial dealers, are a useful but under-appreciated resource for those who keep small insectivorous pets.
Foreign Mantids in the USA
The 2 most-commonly encountered mantids (or mantises) in the USA are both introduced (not native). The largest and most widespread is the Chinese Mantid, Tenodera aridifolia sinensis, brought here in 1896 to battle insect pests. The European or Praying Mantid, Mantis religiosa, arrived as a stowaway around the same time. They and the world’s other 2,400+ species, consume vast numbers of beneficial and harmful insects…in fact, a single Chinese Mantid may consume 20,000 or more insects in its lifetime!
Purchasing and Using Mantid Egg Cases
Millions of Chinese Mantid egg cases are sold annually as a form of biological insect control, but herp keepers have not caught on to their value as a feeder insect. Each egg case will produce 100-400 tiny, soft-bodied hatchlings. Please check this supplier’s website for further information.
The egg cases are quite tough, and need only a daily spraying as care. Best of all, they can be stored in the frig until needed (in the wild, egg cases are produced in the fall, and remain dormant until spring). If not used immediately, the young mantids will feed upon one another, or can be supplied with fruit flies or aphids. Even an occasional feeding of mantids can be of great value to the health of your smaller herps.
Collecting Your Own Egg Cases
You can also collect your own egg cases (usually legal, but check local laws). Begin searching in September (in the USA) and continue throughout the winter. Check fields, weedy city lots and overgrown roadside vegetation…they are usually deposited on tall, stout grasses or shrubs, generally 3-5 feet above ground. The egg cases are well-camouflaged (deer mice and other animals love to eat them) but once you get the right “search image” you’ll find them to be surprisingly abundant in many habitats.
Observing and Keeping Mantids
Allowing a child to watch a mantid egg case hatch will be a thrilling experience for all involved (if you plan to release the insects, do not bring the case indoors until early spring; the young will hatch in mid-winter at room temperatures). I did so just last week, and can assure you that my 3-year-old naturalist cousin had a great time and learned a wonderful lesson (please see photos of him holding an egg case and releasing the mantids).
Mantids are also fascinating captives in their own right. I’ve kept and bred a number of species, and am glad to see they are gaining favor with hobbyists here in the US, and in zoo collections. Please see the article below for details.
Other Insect Alternatives
Lacewings and other tiny insects that are sold to nurseries and gardeners are also potentially useful herp foods. Please check out those offered by the Beneficial Insect Company, and look for my articles on other species in the future. Please also see the article below to learn more about collecting small, native insects. In the meantime, I’d appreciate hearing your ideas and experiences.
Collecting Leaf Litter Invertebrates