A technique is described for rearing successive generations of the insect in numbers from 200 to 40,000 continuously without diapause. All components of the diet are commercially available and the principal ingredients are of plant origin. Survival at four stages of development is given and the causes of mortality are discussed. The per cent survival of insects from instar III to pupation times the percentage of perfect female pupae obtained at harvest gives a factor considered to be the best measure of the worth of an artificial diet. The variability of these statistics is shown by frequency distributions obtained in 50 independent tests of the diet. Overall survival of 84% times 73% perfect females gave a diet worth factor of 61. An analysis of rearing costs is presented. Although 15 continuous generations have been reared, egg production of the highly selected strain has not deteriorated.

The anatomy of the adult of Monodontomerus dentipes Boh., a chalcid parasite of sawfly cocoons in Europe and America, is described. An attempt is made to homologize the structures of this highly modified insect with those known in more generalized insects, in the hope of clarifying some questions of chalcid morphology which has been generally neglected by entomologists. The nomenclature employed is of a kind generally acceptable to students of morphology, an effort being made to eliminate the use of terms specific to a limited group of insects. The anatomy of Monodontomerus is not widely different from that of phytophagous chalcids described by other authors.

No abstract

No abstract

Pse2ldonzonas acrzlginosa is the chief cause of disease in laboratory cultures of grasshoppers. A large number of strains of the bacterium from different localities fell into five types on the basis of reactions with bacteriophages. The five types and their strains were qualitatively similar to one another in morphology, cultural characteristics, and diagnostic biochemical reactions and to a narned culture of P. aeruginosa from the American Type Culture Collection, and their characteristicsagreed with those listed by most authors in the literature a s diagnostic of the species. The strainsand types showed some quantitative differences in production of pyocyanin, development of iridescence, and degree of haemolysis of blood and of hydrolysis of casein. The symptoms of infection and the loss from tnortality are described. The factors influencing the spread of the infection are discussed and methods of suppression of the disease are recommended. The disease originates from a small number of bacteria intimately associated with a very low percentage of grasshopper eggs collected in the field. Nymphs emerging from these eggs die shortly after emergence and contaminate the food supply. Grasshoppers are normally infected by ingesting food contaminated by the bacteria but the bacteria do not multiply in the gut and most of them are rapidly lcilled or eliminated. The bacteria are not actively invasive, but when a small number gain access to the haemocoel they increase in numbers to about 1 X 10"er insect. Shortly thereafter the host dies frorn the metabolic activities of the parasites, most probably as a result of protein digestion by the strong proteolytic enzymes of the bacterium. There is no evidence that the bacteria produce a specific toxin, and grasshoppers are more resistant to the poisonous action of pyocyanin than are mice.'Manuscript