Lots of people know milkweed (Asclepias spp.) as the plant that Monarch butterflies need, or recognize its unique seed pods which open to release many silky little parachutes in the fall and early winter – but there’s so much more to this versatile and essential native plant. Let’s explore some important milkweed species, the insects that rely on them, how to eat them as a vegetable, and more!
Out of 70 or so species of the Asclepias genus native to North America, there are about 13 native to New York State; at least three of these are known to be naturally present here in St. Lawrence County. Common milkweed (A. syriaca) is the most prevalent of these, thriving in successional fields, disturbed areas like roadsides, and occasionally in forest clearings.
Next is swamp milkweed (A. incarnata), in particular the ‘western’ variety (A. incarnata var. incarnata). As the name ‘swamp’ suggests, this species prefers low, wet areas like marshes and swamps, edges of ponds and streams, and poorly-drained parts of fields.
Finally, there is forest milkweed or poke milkweed (A. exaltata), which grows mostly in deciduous forests, especially along roads and paths. It’s not as common as the other two in our area, but you might find some.
Some of the species that are native to other parts of NYS might also be found in our area, due to human cultivation. A couple of these include whorled milkweed (A. verticillata) from the Hudson Valley, Catskills, and Greater Niagara regions; and butterfly weed (A. tuberosa), very popular with gardeners for its striking orange blossoms which are unique among milkweeds. Its native range reaches most of the state, but might not normally come as far north as St. Lawrence County.
Every species of milkweed provides an essential food source to pollinator populations. They attract all the usual suspects – Bumblebees, Honey bees, other native bees and wasps, and Hummingbirds – as well as supporting lots of butterflies and moths.
The native Asclepias in our area, especially common and swamp milkweed, support 12 species of lepidopterans (butterflies and moths). Milkweed is the sole food source for the larvae of Monarch butterflies (Danaus plexippus), but that’s far from all. The Unexpected Cycnia (Cycnia inopinatus) and Milkweed Tussock Moth or Milkweed Tiger Moth (Euchaetes egle) also exclusively rely on milkweed as a host, and it’s crucial to the Delicate Cycnia or Dogbane Tiger Moth (Cycnia tenera) and Lined Ruby Tiger Moth (Phragmatobia lineata) as one of only two or three host plant genera that they use.
Anyone who has grown or been around milkweed has likely seen some other reddish-orange and black insects that frequent these plants. One is the Milkweed Longhorn (Tetraopes spp.), a type of beetle that has specialized to feed on milkweed plants. Its larvae bore into the roots of the plant to feed and overwinter there, and when the adults emerge in late spring they eat the leaves. There are at least three species in the eastern United States – they are very similar, but vary in their amount of black spotting. Read more Milkweed – Native plant of the Week
