Although the mantids devour a large number of honeybees and other beneficial insects, they probably more than make up for this loss by destroying a large number of harmful ones. The eggs overwinter and hatch the following spring. In northern states, there is only one generation a year. Only when they molt to become adults with fully functional wings do they become very conspicuous. The adults can fly.
Most mantids are sub-tropical or tropical.
Less than twenty species occur in the southern U.S. Only three or four species survive in the northeastern states, although several others have been accidentally or deliberately introduced. In Vermont, only one species is known to occur without annual re-introduction. This is the European mantid. It is suspected that heavy, if not complete, mortality occurs in European mantid egg masses not protected by snow, or otherwise against extreme winter temperatures. First observed near Rochester, N.Y. in 1899.