milkweed• Since most other animals avoidmilkweed, the monarch caterpillars usually have the leaves all to themselves.• For the monarchs, Mr Harris brought down from Atlanta a special tall-growing variety of milkweed I had never seen before.• The femaleslay their eggs on milkweed and the caterpillars feed on these plants until they pupate, prior to emerging as butterflies.• The caterpillars of the monarch butterfly, surprisingly, are able to feed on milkweed without taking any of these precautions.• As protection against herbivores such as caterpillars, the milkweed produces chemicaldeterrents on its leaves.• They obtain their unpleasantflavour from the milkweed plant.• In defending itself so thoroughly against the monarch, the milkweed became inseparable from the butterfly.