Tuesday, August 11, 2020

Redbud Caterpillars

Strolling along our lane I looked up at the underside of some redbud leaves and found this colorful little caterpillar.  A quick look at INaturalist identified it as Norape ovina.   Closeup it looks warm and fuzzy but its aposematic colors warn predators and curious humans to stay away from it.  It is a member of the Megalopygidae family whose caterpillars are frequently referred to as "poisonous." To us the risk is from touching them.  Those long fuzzy hairs look soft, even inviting.  They are deceptive, covering upright poisonous setae arising from the yellow bumps. They leave a burning sensation that some liken to a yellowjacket sting.  Some people will have blistering and a long lasting rash.  Hard to believe that this will grow up to be a cute and distinctive moth, the white flannel moth.  Its host plants are redbud and hackberry trees.
 John and Jane Balaban
 
N. ovina is in the same family as the notorious saddleback caterpillar.  Its defense is more obvious with exposed hollow setae, much like tiny hypodermic needles.  At the base of each one there is a there is a poison gland.  One look at this photo by M. J. Raupp should make you go "ouch."
 
Across the drive I found some redbud leaves that were neatly folded with strands of silk.  Inside the was a black and white larva, cuddled up with little pellets of frass.  On close inspection it also had hairs, a single hair for each body segment.  A quick visit to INaturalist identified it as a redbud leaffolder, Fascista cercerisella. 
 
 
 
These caterpillars hide out all day, chewing the upper surface of the leaf which leaves it to brown out until they move to another leaf in the night.  The single tiny hairs are not the least bit threatening so its only apparent defense was hiding out.  That is until I took one home and unfolded a leaf in a plastic dish.  This is a little speed demon, capable of twitching evasive action as seen in this video.
 
Adult leaffolder - Mark Dreiling CC
The adult leaffolder moth is only a quarter of an inch long.  They have two to three generations a year and Oklahoma State's Entoweb describes possible severe damage to foliage.  I suspect this is true in an urban area where there is a single redbud tree but in the valley where I am seldom out of sight of three redbuds, I have to search hard to find any folded leaves.  Once again, this degree of damage has to do with our planting a single tree in an urban area.  Spreading out among the understory of a forest is a much better survival technique for our little racing F. cercerisella.

I kept three cats in a tupperware container, feeding them fresh leaves that they always kept folded up.  Today I was rewarded when I unfolded the leaves and found this pupa inside.  This is the second generation of three so I hope to have the moth climb out this month.