Actually they do. Fleas usually specialize in the mammal (or group of closely related mammals) they feed on. They can survive feeding on other mammals instead, but they will lose fertility to the point of becoming completely infertile. So fleas will always try and stick to “their”mammal if they can.
letsgetawayfromhere t1_j52be4d wrote
Reply to comment by War_Hymn in The Black Death may not have been spread by rats after all by Rear-gunner
Actually they do. Fleas usually specialize in the mammal (or group of closely related mammals) they feed on. They can survive feeding on other mammals instead, but they will lose fertility to the point of becoming completely infertile. So fleas will always try and stick to “their”mammal if they can.