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Wednesday, August 10, 2011

Milkweed Munchers

One thing I look forward to in August and September is the welcome visits from the monarch butterflies.

In order to attract types of butterflies, nectar sources for the adults and host plants for their caterpillars have to be available.

Milkweed (Asclepius) is the only host plant utilized by monarch caterpillars. The genus name honors the Greek God Asclepias, the God of Medicine. Native Americans and others used milkweed medicinally. Though poisonous in large doses, it was used for kidney and bladder problems, pleurisy, as well as to increase perspiration to reduce fever.

The sap from the leaves of milkweed is toxic to many insects and other predators, but those that feed on the plant can safely absorb the toxins. They are then found to be distasteful to anything that attempts to feed on them. Most people don’t realize that milkweed is also a host plant for many other insects.

The tussock moth caterpillar is visibly cute to observe, being a furry little eating machine.

The distinctive coloring of shades of red or orange are a sign to predators that says, 'Leave me alone, I'll make you sick'.

A member of the longhorn wood boring beetle family, the red milkweed beetle is easy to identify as it has a characteristic easy to identify, four eyes instead of two. Long antennae are so close to the eyes that they actually split each eye in two.

 Milkweed leaf beetles are distinctively marked, large orange and black. They resemble an oversized lady beetle but are from a different family called the leaf beetles. They are commonly called "swamp" milkweed beetles, after their preference for the swamp milkweed.

Gray in appearance is the milkweed stem weevil. They feed on the milkweed stem by girdling the stem, then feeds on the oozing sap.

Last to mention are the seed bugs, which include the large and small milkweed bugs. These insects nibble the seeds of the milkweed flower. Like the sap, the seeds are harmless to the bugs but dangerous to their predators.

Milkweed has various varieties but it is best to plant natives to your area. They are easy to grow, needing well-drained soil and a sunny to partly shady spot. By fall, the seedpods burst, sending out copious quantities of seeds which easily reseed.

Your common milkweed (Asclepias syriaca)

Swamp milkweed (Asclepias incarnata)


Butterfly weed (Asclepias tuberosa)

Dogbane (Apocynum cannabinum) resembles milkweed but isn't an Asclepias. Apocynum means 'poisonous to dogs'. Cannabinum is the scientific name and the common names are Hemp dogbane and Indian hemp. It is a fiber plant rather than a source of the psychoactive drug, Cannabis. Both have white sap, but milkweed has hollow green stems and dogbane has solid red stems. Monarch caterpillars won't even eat dogbane.

 Are these 'good' bugs or 'bad' bugs? It depends upon what you consider to be good or bad. Since the Milkweed Bugs are seed and sap-suckers, if bugs chomp and deform the milkweed in your garden, you may consider them 'bad' bugs. Host plant or not, you may not want them in your garden and squish them. Just please don't use pesticides to control unwanted visitors. You will be harming those you do want such as the monarch butterfly caterpillars. It is a natural occurrence for the host plant to be fed upon and it is only temporary.

Enjoy the amazing process of metamorphosis and take pride in providing the means for the survival of these insects. If you're a collector of the Asclepias seed pods and need them unmarred, handpicking a few select plants to keep them bug free would be the best option.