# Monarch butterfly

*Danaus plexippus*

The reason most people plant milkweed, and the only butterfly whose caterpillars cannot eat anything else.

## What it does on milkweed

Monarch caterpillars are obligate feeders on milkweed. They eat the leaves, tolerate the cardenolides that would stop the heart of most animals, store those toxins in their own tissue, and advertise the fact in orange and black. Adults are not fussy about nectar and will feed at almost anything in flower, but the egg goes on milkweed or the larva starves.

## How to recognize it

Adults are orange with heavy black veining and a black border set with white dots. Caterpillars are banded in yellow, black and white, with two pairs of black filaments, longer at the head end than the tail. The chrysalis is jade green with a line of gold dots.

## Where and when

Every state except Alaska. Eastern populations winter in the oyamel fir forests of central Mexico; western populations winter in coastal California groves.

## Should you do anything about it?

Nothing to do but plant more milkweed and stop spraying. Chewed leaves are the plant working.

### Will monarch caterpillars kill my milkweed?

No. A mature milkweed regrows readily after being stripped, and most plants are eaten well after they have flowered. Container plants and first-year seedlings are the exception, and can be overwhelmed.

### How many caterpillars can one plant support?

A large common milkweed can feed several to maturity. Plan on roughly one caterpillar per good-sized stem, and plant in groups of at least ten stems.

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Source: https://milkweedusa.com/wildlife/monarch-butterfly/ — Milkweed USA, CC BY 4.0.