F. fusca , which they habitually make into slaves, from those of the little and furious F. flava , which they rarely capture, and it was evident that they did at once distinguish them; for we have seen that they eagerly and instantly seized the pupae of F. fusca , whereas they were much terrified when they came across the pupae, or even the earth from the nest, of F. flava , and quickly ran away; but in about a quarter of an hour, shortly after all the little yellow ants had crawled away, they took heart and carried off the pupae.