CONTENTS. 5 



Department Bulletin No. 808. — Studies on the Life History and 

 • Habits of the Jointworm Flies of the Genus Harmolita (Isosoma), 



WITH Recommendations for Control: Pago. 



Introduction i 



Species infesting the grain crops. _. 2 



The wheat jointworm {Harmolita tritici Fitch) 2 



The wheat strawworm (H. grandis Riley) 5 



The wheat sheath-gall jointworm (H. Vaginicola Doane) 8 



The barley jointworm (H. hordei Harris) li 



The rye jointworm (H. secalis Fitch) 13 



The rye strawworm (H. websteri Howard) '. ]4 



Species infesting the cultivated grasses 15 



The timothy strawworm (H. albomaculata Ashmead) 15 



The orchard grass strawworm (H. dactylicola Phillips & Emery) 16 



The blue-grass jointworm (H. captiva Howard) IG 



The blue-grass strawworm (H. poae Phillips & Emery) 17 



The festuca jointworm (H. festucae Phillips & Emery) 18 



Species infesting wild grasses 19 



Harmolita maculata Howard 19 



H. atlantica Phillips & Emery 19 



H. agropyrophila Phillips & Emery 20 



H. elymi French 20 



H. elymicola Phillips & Emery 21 



H. elymivora Phillips & Emery 21 



H. rufipes Phillips & Emery 21 



H. hesperus Phillips & Emery 22 



H. elymophthora Phillips & Emery 22 



H. ovata Phillips & Emery 22 



Species whose biology is unknown 23 



Control measures ; . . . 23 



Literature cited .■ 26 



Department Bulletin No. 809. — American Foul Brood: 



Introduction 1 



Name of the disease 2 



Healthy brood at the age at which it dies of American foul brood 3 



Symptoms 5 



Etiology 11 



Technique 17 



Thermal death point of American foul-brood spores 22 



Resistance of American foul-brood spores to drying 29 



Resistance of American foul-brood spores to direct sunlight 29 



Resistance of American foul-brood spores to fermentation 31 



Resistance of American foul-brood spores to chemical disinfectants 31 



Effect of drugs on American foul brood 32 



Modes of transmission 34 



Diagnosis 36 



Prognosis ' 38 



Summary and conclusions 39 



Literature cited 42 



Explanation of plates 45 



Department Bulletin No. 810. — European Foul Brood: 



Introduction 1 



Name of the disease 2 



Healthy larvae of the age at which they die of European foul brood 3 



Symptoms 4 



Etiology 7 



Technique 15 



Thermal death point of Bacillus pluton 17 



Resistance of Bacillus pluton to drying 17 



Resistance of Bacillus pluton when dry to direct sunlight 19 



Resistance of Bacillus pluton in water to direct sunUght 20 



Resistance of Bacillus pluton in honey to direct sunlight 21 



Resistance of Bacillus pluton to fermentation 21 



