Monday, July 23, 2012

Incredible Edible Milkweed

Monarch Butterfly feeds on nectar from Common Milkweed flowers
Milkweed plants are some of the most important wild plants that grow in the environment –this is according to the plants’ biggest fans --the insects themselves.
Hickory Hairstreak Butterfly on Common Milkweed
There are several species of milkweed that grow in different habitat niches around our nature preserve; by far the most common is “Common” Milkweed. This variety grows in fields and pastures, and even has a tendency to sprout up in any piece of disturbed open ground. Common Milkweed is also the most utilized by insects, both as a nectar source and as a food plant.
The Eight-Spotted Forester Moth on Milkweed flowers

Common Milkweed often grows in colonies or clumps –connected by underground roots called rhizomes.

Swamp Milkweed is the second most common Milkweed species at our preserve. It is much more selective in its habitat, and grows primarily in wetland situations. It usually grows taller than Common Milkweed and its redder flowers are often located on the very top of the plant.
Swamp Milkweed has much  pinker blooms
The stouter Butterflyweed has lush orange blossoms and is currently the rarest milkweed species at our preserve. I had originally introduced it as a meadow plant but never managed to get it established in the heavy clay soil of our fields. Whorled Milkweed is another native variety that I tried to introduce a decade ago but with little success.

The number of pollinators that visit Common Milkweed for nectar is huge. In fact, a great way to find a diverse collection of insects (mostly bees, wasps, beetles, moths and flies) in a given area is to stake out a patch of Milkweed. The sticky flowers sometimes trap pollinators –most often by the leg. Still, most do manage to tug themselves out.
Acadian Hairstreak Butterfly on Butterflyweed

The Monarch Butterfly has lent milkweed a certain amount of fame as that enigmatic butterfly’s main food plant, but there are also other insects which almost exclusively eat that plants leaves.

A very young Monarch caterpillar feeds on a milkweed leaf

Early stage (or instar) of the Milkweed Tussock Moth feeding on Milkweed
One of the insects that make a living off of milkweed leaves, is the Milkweed Tussock Moth. Unlike the Monarch's eggs, which are laid individually by the female butterfly, the tussock moth lays a great quantity of eggs upon its host plant. Upon hatching, the tiny moth larvae feed together on the milkweed  –skeletinizing the plants leaves.

An older Milkweed Tussock Moth caterpillar - note the tufts of hair
At first the Milkweed Tussock Moth’s  caterpillars are light in color, and resemble the larvae of sawflies, which also typically feed in large groups. After molting, the new skin of the tussock moth is covered with relatively long black, white and orange tufts of hair. These hairs are an irritant to the digestive tracts of birds and thereby they lend protection from the insect’s main group of would-be predators.

2 Milkweed Beetles mating on a milkweed leaf
Red Milkweed Beetles are fairly large red beetles with prominent black spots and very long curved, black antennae. In fact they are one of the species known as long horn beetles. These fairly comical looking creatures are never found far from the milkweed leaves that they consume. As is the case with the Monarch, It is thought that the toxins in the milkweed plant make these beetles less palatable to predators.

The long curved antennae  of the Milkweed Beetle
Interestingly, Monarch caterpillars have long black, curved antennae-like projections coming off of their backs –right behind their heads. These false antennae jerk around as the caterpillar feeds. This movement contributes to an illusion and helps the caterpillar stay alive by deceiving predators into thinking that there is a more formidable long-horned beetle feeding behind the leaf and not a defenseless butterfly larva.
The long false antennae of the Monarch caterpillar
The Milkweed bug walking on an Indian Hemp plant
The Milkweed Bug is another insect species that lives primarily on the juices of Milkweed. Sometimes I find large groups of these little guys in places other than on Milkweed plants. In an earlier stage of their life cycle, before undergoing metamorphosis, their appearance is quite different. But in all stages, the Milkweed Bug always show a considerable amount of red on their bodies, and this is thought to advertise how distasteful they are to predators.
An early instar (or nymph) of the Milkweed Bug
Swamp Milkweed Leaf Beetle
The Swamp Milkweed Leaf Beetle is also found on Common Milkweed. This is yet another red beetle that feeds primarily on milkweed foliage. It is said that before they begin feeding on a leaf, they cut the leaf's primary veins in order to prevent an abundance of toxic sap to accumulate.

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