Studies of Hypoderma lineatum and Hypoderma bovis with especial reference to economic importance and control

Abstract

1. Hypoderma lineatum and Hypoderma bovis are prevalent in Burkes Garden and Southwestern Virginia generally. 2. Young cattle, calves and yearlings particularly, are generally more heavily infested than older cattle. 3. Adults appear in Burkes Garden the first warm days in April though they are at their worst in June and July, a normal season. 4. Larvae ordinarily make their first appearance in the subcutaneous tissues of the back about the first of December. The first ones emerge and pupate about the middle of January. 5. At the time control was started H. lineatum exceeded H. bovis in the ratio of 65 to 35 percent. The ratio now is 55 to 45 percent. 6. Salt, wet or dry, is an ineffective dressing for killing Hypoderma larvae in the subcutaneous tissues of the host. 7. Benzol, 90 or 100 percent, injected into larval cysts effects a high percentage of kill. 8. Hand extraction at intervals of 30 days repeated five times is a practical and effective means of control. 9. Hand extraction performed by the average farm worker caused an occasional case of anaphylaxis, .037 percent 10. Cooperative control measures, to be effective, should be supervised closely. 11. Extraction of Hypoderma larvae from the subcutaneous tissues of the host effects gains in weight and milk flow advantageously. 12. Control measures as practiced in Burkes Garden has reduced Hypoderma infestation by approximately 50 percent.