354 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



up a leg and take hold of it. Since they live in the soil, these grubs 

 would never be eaten naturally. Freshly killed insects will be eaten, 

 if offered on a stick or in tweezers, but mantids do not ordinarily pick 

 up immobile bodies of insects from the floor of a cage. Water should be 

 sprinkled on the cage each day or given the mantid with a medicine 

 dropper. 



It is more difficult to rear mantids directly from eggs, because the 

 young are delicate and much more limited in their choice of food. 

 Furthermore, people often have eggs that have been taken indoors 

 during winter when the average person has no supply of suitable in- 

 sects available as mantid food, so that, while the little mantids hatch 

 by the dozens readily enough at living-room temperature, after 2 or 

 3 days they begin to starve rapidly. The atmosphere of many houses 

 is too dry in winter for the mantids to do well. If a serious attempt 

 to rear mantids to maturity from eggs is to be made, a little planning 

 is necessary. A supply of small insects can be assured by establish- 

 ing a culture of fruit flies {Drosojyhila) in jars containing fermenting 

 bananas or other suitable fruit. Each day a few living flies are trans- 

 ferred to the mantid cages. Plant lice from greenhouse or other 

 plants may also be fed to the newly hatched mantids, being transferred 

 directly on twigs or other host plant materials. A great variety of 

 leafhoppers and other small insects may be swept with an insect net 

 from grass. Larger insects may be supplied as the nymphs grow. In 

 a rearing experiment with Stagmomantis limbata (Hahn) it was 

 found (Roberts, 1937b) that the consumption by one mantid during 

 its entire life averaged over 700 insects. 



Nymphs usually refuse food for the first 12 to 24 hours after hatch- 

 ing, and for a day immediately before and after molting. Mantids 

 rear well at a temperature of 75'' to 88° F. and with a relative humid- 

 ity of 50 to 70 percent. Dryness may be partly offset by spraying 

 water lightly from a small atomizer over the nymphs and their cage 

 once a day. Too much water will drown them in the first nymphal 

 stage. Unless they are overcrowded or underfed cannibalism is not 

 common until the nymphs are half grown. After the fifth molt, only 

 one or two nymphs should be kept in the same container, and adults 

 should be separated if cannibalism is to be avoided. Care should be 

 taken to avoid infestation of cages with ants; the latter are very 

 dangerous to newly hatched mantids. A tiny mite, Pyemotes ventri- 

 cosus (Newport), has attacked mantids in some rearing experiments 

 (Rau and Eau, 1913). 



ECONOMIC IMPORTANCE 



The majority of insects normally eaten by mantids are probably 

 injurious to gardens or other agi-iculture, so that mantids as a whole 

 are beneficial insects. It is true, however, that a portion of their 



