What is the name of the poison in the monarch butterflys body and how potent is it?
A. The monarch stores a poison called cardenolides, or cardiac glycosides that it gets from the plants it eats. This poison is similar to digitalis, which can be used to help people with heart problems, but can kill people if they consume too much of it. These are poisonous to most vertebrates (animals with backbones), but they may not be poisonous to invertebrates (animals without backbones). The potency of monarchs depends on the potency of the plants they ate when they were caterpillars. Some kinds of milkweed have higher levels of cardiac glycosides than others. The effect of the toxin depends on the amount of toxin that the predator eats, and what kind of animal the predator is. Q. Are there any that can and do regularly eat monarch butterflies or catepillars? A. Yes. There are some birds that eat monarchs, some mammals (mice), several insects, and some parasites. We have a good section on predation in the Monarch Watch website (see address at the beginning of this message). We do
