Sunday, September 14, 2014

Wooly Bear Caterpillar Weather Predictor?

 Wooly Bear Caterpillars are busy finding a place to hibernate for the winter, and walk busily in front of anything in their search. So lots of sightings are being made now.   Here are pictures of two caterpillars I have found in the last few days.

Folklore seems to have made sure that everyone hears the story that the amount of brown on these caterpillars is a predictor of how severe the winter will be.
Supposedly, more brown means a less severe winter.

Here in Minnesota we are always looking for a reliable winter prediction, even if from a caterpillar.

Folklore is fun and will persist, but science and observation helps to give some understanding of why these caterpillars may look different sometimes.

Eggs are laid in late summer and early fall when these caterpillars hatch and start to grow.

After hatching they eat several plants that grow in our lawns, and shed their skins as they grow.  They shed 6 times, and each time the black bands get wider and the brown gets narrower, but the furry bristles get thicker with each shedding as well. 

When cold weather sets in the caterpillar finds shelter under some bark or other protected place and hibernates, freezing solid!

When warm weather returns the caterpillars revive, eat a little, then form a cacoon, and after a few weeks an Isabella moth emerges, and the cycle starts over.

So, what do you think?  A long hard winter or a short easy one?

Friday, September 12, 2014

Tiger Swallowtail Butterfly Caterpillar

 Almost everyone has seen the beautiful and gracefull Tiger Swallowtail butterflies that visit our gardens in mid summer. 

As the flowers and warm weather have dissappeared, the butterflies have as well.

 I saw this old and bedraggled looking one last week in the prairie.  I was surprised it could still fly from flower to flower.

While these butterflies are now gone their caterpillars are finishing growing and looking for a place to make a chrysalis for the winter. 
 Tiger Swallowtail butterfly caterpillars have some distinctive features.

They are a basic green like many caterpillars, but they have special "eye" markings to use in defensive situations.

When danger approaches they pull their head back into their body, swelling the front part of their body, making it look like the scary picture below.

If that doesn't work the caterpillars have brightly colored orange scent organs they extrude from their head that emit a bad odor. 

It's defenses seem to be working for this caterpillar so far.