Saturday, October 17, 2015

I Goofed, Red Spotted Purple Update

So I noticed the caterpillar seemed to make an abrupt jump in its development. I made an assumption that as long as the apple tree I found it on had leaves, then this caterpillar would happily eat them. What I forgot though was the average temperature and amount of day light were also factors.

Posing the question of when I should put this one in the fridge to over winter, I learned I should have done that a week ago when it was in the third instar. Apparently that is the instar that they go into hibernation. Unlike species who spend winter in the chrysalis stage, the number of hours in the day when the sun is shining as well as the temperature determine whether or not they should hibernate or move on to further instars and adulthood.

Tragically my caterpillar is well into its 5th instar and I'm told nothing will stop it now from developing into a chrysalis and emerge into an adult 7 to 10 days later. This species does not migrate and by then it will be late October or early November, when it is too cold to release, and the host tree (a White Snowdrift Crabapple) will likely have lost all its leaves. I suppose I will have to let it happen and keep the butterfly captive until it expires. I'll try and keep it alive by offering it pieces of rotting fruit, and eventually pin it I guess.

Speaking to its host plant for a moment. The little crabapples have turned orange and the birds are already eagerly pecking away at them. Lots of the leaves are now covered in damaged fruits as well a surprising amount of bird droppings. I wonder if actually having real bird crap around makes the disguise this caterpillar produces more or less convincing.

There are likely two or tree more Red Spotted Purple caterpillars on the tree, but as they're likely just in their third instar, I'll have to wait until the leaves fall off of the tree to look for them. My understanding is the "shed" they make by rolling a leaf around them with silk does not fall off of the host plant. If I find a few, I'll be sure to collect and store in my fridge until the tree leafs out and flowers the next year.