One day, my mother-in-law was strolling around the yard with me when we came to a large milkweed plant in the middle of what little lawn I have. She asked me, with much surprise, “Are you keeping this?”

I didn’t know whether it was the placement of the plant (coming up in the grass) or whether it was the type of plant (a “weed” to most folks) that made her think I shouldn’t want the milkweed there, but it didn’t matter. I knew that particular milkweed held a tiny treasure that I was delighted to have in my yard. I would never consider destroying such a valuable plant!

A minuscule (less than 4 mm long) monarch caterpillar was eating its way toward adulthood on that 4-foot-tall plant. It belonged to the last generation of the season and would fly to Mexico before freezing weather set in. I felt proud that my milkweed was helping to sustain the population of this tropical butterfly that can’t survive the winter in our area.

Common milkweed (Asclepias syriaca) is an early-summer flowering plant that comes up in dry fields and along roadsides, usually growing 3–5 feet tall. While the overall impression you might have of these plants from a distance is one of coarseness, a closer look reveals beautiful, goblet-shaped, pink flowers that perfume the air with a wonderful scent.

The blooms hold lots of nectar, which is especially alluring to bees and butterflies. Silver-spotted skippers, great spangled fritillaries, zebra swallowtails, American ladies, tiger swallowtails, Eastern tailed blues, and spicebush swallowtails are some of the butterfly species that you might see visiting.

You may even spot an unfamiliar species that you have not seen in your yard before. On June 18, 1999, I saw my first-ever variegated fritillary nectaring at common milkweed. This lovely butterfly spent the afternoon feeding in my milkweed patch before moving on. And, of course, milkweed will bring in the monarch butterfly whose caterpillar can eat only milkweed plants to survive.

The monarch has suffered very serious declines over the last several years, with 2013 being catastrophic. The clearing of the Mexican fir forests where these insects overwinter, in combination with the continued displacement of “weedy” habitat in this country, have made their prospects dim.

Gardeners can help save this disappearing species by growing milkweeds, especially the widespread common milkweed. These plants come up in spring, just in time for northward-migrating monarchs to lay eggs on them.

It should take about 13 days for the eggs to hatch, but that may vary, depending upon the weather. The teeny-tiny, colorful caterpillars are striped in black, yellow and white.

But monarchs are not the only interesting insects to be found on common milkweed. Orange-and-black insects known as large milkweed bugs may appear by the time that the green seedpods have begun to form. Or you may see small milkweed bugs that are red and black. Both insects pierce the pods to suck the juices from the developing seeds inside.

After you have seen milkweed bugs mating, you can keep an eye on the seed pods where the immature ones will appear. They will stay there for quite some time, which means you can check every day or so to watch them develop.

I usually see one or more adult large milkweed bugs with their nymphs (the immature milkweed bugs) until well into fall. The adults appear to be watching over the young ones, which is extremely unusual behavior in the insect world.

An interesting phenomenon associated with the common milkweed is that many of the creatures feeding on these plants are orange, including a species of aphid. A few organisms are red—the color which is closest to orange on the color spectrum.

Milkweed sap contains alkaloids that make monarchs that feed upon it somewhat poisonous to predators.

The fertilization process in common milkweed is so complex that very few flowers ever get fertilized. From each cluster of up to 75 blooms, only two seed pods will normally develop.

I highly recommend that you grow common milkweed. Then perhaps a monarch laying eggs will alert you to the plants emerging from the ground and soon, you too, could be able to enjoy seeing “tiny treasures.”

Distributed by Bay Journal News Service.