Acrididae 291 



to properly suspend itself, causes trouble at ecdysis. The loss of a leg is 

 not so serious for an adult as for a nymph. 



3) Food. An abundance of suitable food should be present in the 

 cages at all times, either growing in soil or kept fresh in water. If water 

 is used, care is necessary to prevent the insects from drowning. Tryxa- 

 lines and oedipodines feed mostly on grasses. Various species of Poa 

 and Andropogon are suitable. Wheat and millet are satisfactory and 

 readily grown in small flower pots in the laboratory. Oats are totally 

 unsuitable, as are some grasses. Dandelion, plantain, and clover are 

 good for giving variety. Lettuce and apple will tide many species over 

 a period of food scarcity. For some species lettuce will serve as the chief 

 food. These foods are adequate for the previously mentioned acridines 

 also. But many of this group are highly specialized in regard to their 

 food plants. Hypochlora alba is restricted largely to Artemesia jrigida, 

 Hesperotettix speciosus to sunflowers, H. viridis to Grindelis and certain 

 species of Solidago, H. pratensis to a different Solidago. In fact, the 

 experienced collector in this group looks for the food plant of the species 

 sought rather than the animals themselves when starting to collect in 

 a new region. 



4) Diseases and Parasites. The chief dangers to laboratory cultures 

 are diarrhoea caused by an Amoeba (recently described by R. L. King) 

 which may wipe out cultures during cold damp periods, and molds which 

 thrive in damp places in the absence of sunlight. Hyphae of the fungi 

 grow throughout the body cavity. Gregarines also cause trouble, espe- 

 cially when cages with damp sand and much debris are kept at a con- 

 stant high temperature as in an incubator. Nematodes, too, sometimes 

 become troublesome, especially if the cultures are fed on grass brought in 

 from a cool, damp place and put into the cages without a thorough 

 washing. And, finally, a small parasitic wasp may attack the eggs. 

 It thrives chiefly on dead eggs and I am not sure that it ever attacks 

 those in a healthy condition. It is more apt to be present when soil is 

 used in place of clean sand for the eggs. 



None of the above troubles is a serious menace to cultures which are 

 given proper care. In case the insects start to die transfer them daily 

 to cages which have been washed and sterilized in very hot water, dis- 

 card all individuals which are obviously sick, and correct faulty cultural 

 conditions. 



