Common Milkweed: A Frequent Stop

From May until October, Common milkweed is one of the flowers that I stop at regularly on my rounds in Eliza Howell Park. From being a “weed” in need of eradication, it has in recent years acquired both respectability and fame as a host plant for the larvae of the popular Monarch butterfly. I watch it for that role and for many other reasons.

In September, the plants, many of them 4 feet tall, are dominated by follicles (seed pods).


When the seed pods open – and some are just beginning to do so – we can witness the delicate beauty of the seeds attached to the silk that allows them to be dispersed by the wind. This is definitely worth seeking out a sunny fall day.


Common Milkweed is a perennial wildflower native to eastern North America that spreads both by seeds and by underground rhizomes, the second being the reason they are often found in patches. They sprout in May, usually shortly before the Monarchs return. (This year I saw the first Monarch on May 15.)


Monarchs start laying eggs on the milkweed leaves almost immediately after arrival. Once hatched, the larvae (caterpillars) eat the tender leaves. This picture of a tiny caterpillar is from early June.


By the end of June, milkweed is beginning to flower. I was especially struck this year by how fragrant the flowers are. Even for someone like me, who does not have the most sensitive nose, it is easy to know that one is in a patch of blooming milkweeds from the fragrance alone.



Milkweeds get their name from the fact that leaves and stems, when broken, produce a milky sap. There is a toxicity in the milkweed plant and Monarchs acquire this toxicity from ingesting the leaves as caterpillars. The result is that adult Monarchs are not preyed upon by birds, who have come to know that Monarchs are not healthy food.

Monarch butterflies are not the only insect that benefits from using Common Milkweed as a host plant for young. In September, it is easy to find seed pods covered with Large Milkweed Bugs. In the picture, the left shows adult Large Milkweed Bugs and the right picture is of young ones (nymphs). (Yes, there are Small Milkweed Bugs, but not in this entry.)


Large Milkweed Bugs have some characteristics similar to Monarchs: milkweed is the host plant on which the young feed; they are orange and black; they acquire a protective toxicity from milkweed; they migrate south for the winter.

I have recognized Common Milkweed for as long as I can remember, but I have only really gotten to know it from my observations in Eliza Howell Park in recent years. The more I know about it, the more I like it.