Summer view

Summer view
A View From Our Deck

Tuesday, August 29, 2017

Have You Seen A Milkweed Tussock Moth Caterpillar?

I have written a lot about Monarch butterflies in previous posts and the fact that I let milkweed plants grow where ever they want in my yard and garden.  It is my little way of helping the declining Monarch population.  If you want to read some of the posts I have written about Monarch's, just type monarch butterfly into the search box.  If you have milkweed plants, you have probably noticed  caterpillar eating on the leaves that looks different from the Monarch caterpiller.  They are called a Milkweed Tussock Moth caterpillar.  Another name is Milkweed Tiger Moth.  At first I thought it was a tent caterpillar because the color was similar.  Looking more closely I saw all the hairs.  When the Monarch butterfly caterpillar, the Milkweed bug and the Milkweed Tiger Moth caterpillar eat the leaves of a milkweed plant, they are ingesting a highly toxic chemical.  The milky sap in the plant is poisonous to humans and animals.  Birds feast on a lot of different insects but somehow they know not to eat Monarch butterflies, Milkweed bugs or the Tiger moth.  They retain the poison even after changing from a caterpillar into the moth or butterfly.  Predators learn that the orange and black color is a warning, and they shouldn't eat them.  Bats also like to eat insects but they can't detect the orange and black in the dark.  Amazingly the milkweed tiger moth has an organ that emits an ultrasonic signal easily detected by bats. This signal warns the bat of a toxic bad tasting meal and bats soon learn to avoid the tiger moth.  The tiger moth caterpillar turns into a drab brown moth but the signal they emit protects them at that stage of life.

The milkweed tussock or tiger moth caterpillar.

The leaves of this milkweed are being eaten off.

All the leaves are gone from this plant, but the seed pods remain.

I think these caterpillars could be very destructive.  They can eat the leaves off a whole plant very quickly.  Fortunately they leave the seed pods which will burst open soon leaving the wind to distribute seeds which will turn into new plants next Spring.