Executive Hafner stared unhappily into the cage. It was an undistinguished animal, small and something like an undeveloped rodent. Its fur was sparse and stringy, unglamorous; it would never be an item in the fur export trade. "Can we exterminate it?" asked Hafner. "Locally, that is." "Hardly. It's ecologically basic." [Illustration] The executive looked blank. Dano Marin added the explanation: "You know how Biological Control works. As soon as a planet has been discovered that looks suitable, they send out a survey ship loaded with equipment. The ship flies low over a good part of the planet and the instruments in the ship record the neural currents of the animals below. The instruments can distinguish the characteristic neural patterns of anything that has a brain, including insects. "Anyway, they have a pretty good idea of the kinds of animals on the planet and their relative distribution. Naturally, the survey party takes a few specimens. They have to in order to correlate the pattern with the actual animal, otherwise the neural pattern would be merely a meaningless squiggle on a microfilm. "The survey shows that this animal is one of only four species of mammals on the planet. It is also the most numerous." Hafner grunted. "So if we kill them off here, others will swarm in from surrounding areas?" "That's about it. There are probably millions of them on this peninsula. Of course, if you want to put a barrier across the narrow connection to the mainland, you might be able to wipe them out locally." The executive scowled. A barrier was possible, but it would involve more work than he cared to expend. "What do they eat?" he asked truculently. "A little bit of everything, apparently. Insects, fruits, berries, nuts, succulents, and grain." Dano Marin smiled. "I guess it could be called an omnivore--now that our clothing is handy, it eats that, too." Hafner didn't smile. "I thought our clothing was supposed to be verminproof." Marin shrugged. "It is, on twenty-seven planets. On the twenty-eighth, we meet up with a little fella that has better digestive fluids, that's all." Hafner looked pained. "Are they likely to bother the crops we plant?" "Offhand, I would say they aren't. But then I would have said the same about our clothing." Hafner made up his mind. "All right. You worry about the crops. Find some way to keep them out of the fields. Meanwhile, everyone sleeps in the ship until we can build dormitories." Individual dwelling units would have been more appropriate in the colony at this stage, thought Marin. But it wasn't for him to decide. The executive was a man who regarded a schedule as something to be exceeded. "The omnivore--" began Marin. Hafner nodded impatiently. "Work on it," he said, and walked away.