Milkweed poison is harmful to sheep, cattle and sometimes horses, especially when eaten in bulk.
Some people are sensitive to the sap. But wear gloves and you will be fine.
The monarch caterpillar is at a high risk when they eat Milkweed. Milkweed got its name because its full of a sticky milk colored liquid. Many caterpillars get stuck in it and die. The caterpillars that eat milkweed are immune to a special toxin in the milkweed but still are at risk of dying in the sticky liquid. Butterflies do not eat milkweed. They drink nectar from flowers or juice from fruits.
There are chemicals in the milkweed that make it taste or smell bad
They are a native insect that naturally feeds on milkweed plants. If by "bad" you mean are they an invasive or pest species, then no, they are not bad. Some people are allergic to their hairs though, so be careful with them...
He is not venomous.
Milkweed pollen is not much of a problem but some people have a contact allergy to the leaves and sap.
There is common milkweed, purple milkweed, tropical milkweed, and swamp milkweed.
The white liquid milkweed secretes when cut -- and other parts of the plant -- contain a cardiac glycoside much like the one found in digitalis (foxglove). This toxin interferes with the calcium and potassium channels, and modifies the heart rhythm. Some wild food references indicate that milkweed flowers and immature pods can be safely prepared for eating. However, I'm hesitant to trust this information. So yes -- milkweed is toxic to humans.
CAse
Yes. There is milkweed in Jamaica. The Jamaican Monarch lives on milkweed.
It isn't the bad food that makes you sick but what bacteria is growing in it. It can be Botulinum which makes a toxin that is the most powerful neurotoxin known to date. Only one single molecule of it is needed to stop one neuron working.1 gram of botulinum toxin would be enough to kill 14,000 people (if ingested), 1.25 million people if inhaled, or a staggering 8.3 million people if injected.
Milkweed is not a decomposer.
Two to three years is the length of time which milkweed needs to grow. The Asclepiadaceae family member in question numbers among the world's broadleaf perennials. The Asclepias genus member in question there survives a couple or few years, depending upon eco-system health and plant well-being.