290 Phylum Arthr op oda 



acridines are limited to certain weeds as food plants. These plants in 

 turn are restricted to given soil and climatic conditions. Alkalinity or 

 acidity of the soil is often a limiting factor for the plants. In case it 

 is desirable to use a restricted species away from its normal habitat, 

 not only seed or young specimens of its food plant should be take but 

 also soil should be shipped or at least samples taken for analysis so that 

 the necessary constituents may be added to the soil in the new locality. 



4) Number of generations per year and size of broods. Some species, 

 like Hesperotettix viridis, lay only 5 to 8 eggs per pod and one female 

 does not make more than 6 pods, so that, if there is normally only one 

 generation per year, a given female will not produce more than 40 off- 

 spring. Most oedipodines lay from 15 to 24 eggs in a pod and produce 

 3 to 4 pods, so that one female may have as many as 75 offspring. 

 Furthermore, some southern species, already mentioned, may produce 

 6 to 8 generations per year in the laboratory, although they probably do 

 not produce so many in nature. 



Melanoplus differentialis, M. bivitatta, and Romalea microptera fe- 

 males on the other hand lay as many as 150 eggs in the first pod and a 

 given individual may make 3 pods each with progressively fewer eggs. 

 Such females will produce from 200 to 300 offspring. Fortunately 

 they are restricted normally to one generation per year. 



III. Life Cycle. Three well defined stages occur: 1)— Embryonic, 

 extending from the first cleavage of the egg until hatching. Some eggs, 

 as noted by Nabours for tettigids and Slifer and King or M. differen- 

 tialis, develop parthenogenetically. Most northern species hibernate 

 over winter in the eggs. 2) — Nymphal, from hatching to the last molt, 

 marked by 5 instars during which progressive development of pre- 

 existing structures takes place. Certain species hibernate for the winter 

 in the 2nd and 3rd instars. 3)— Adult, extending from the last ecdysis 

 until death. Usually an individual does not live more than 3 months 

 after becoming an adult. 



IV. General Care. In order that experimental results may be valid 

 the stock must be healthy. The following suggestions may help to 

 attain that end. 



1 ) Cleanliness. Debris should be removed and clean dry sand should 

 be scattered on the floor of the cages at least once each week. Except 

 during egg-laying the cages should be kept dry. Warmth and sunlight 

 are essential. 



2) Handling. Shell vials are convenient for capturing the young 

 insects when it is necessary to study or move them about. Older ones 

 may be caught gently by the thorax or wings with the fingers. Never 

 catch them by the jumping legs since these are readily detachable. The 

 blood clot which then forms, as well as the inability of the crippled insect 



