Monday, September 12, 2016

Monarch Watch-out

Monarch caterpillars - Ethan Welch
Holly Welch and her son have been photographing their Monarch caterpillars as they headed to pupation and a not-so-funny thing happened on their way to that form.


Orange wing showing - Becky Arnoldy
First the good news.  She went out on Labor Day and found one of the cats that had wandered off to pupate on the house siding.  A few hours later it had transformed to the jeweled pendant of a chrysalis.  When you see one wander away from feeding, watch carefully and you may be able to see the marvelous transformation.  Keep watching and you may be able to catch the final act of the chrysalis before the grand opening.  It changes color and shows the wings as a coming attraction.

Anchor Stink Bugs dining on Monarch cat - Holly Welch
  Mike Quinn CC
Now the bad news.  Holly went out Sunday and while taking the chrysalis pictures captured this image above.  She identified it as Anchor Stink Bugs (ASB), Stiretrus anchorago, attacking their beloved cats.  You can see that it is shriveling up as the bugs' proboscis are sucking out its juices. 
 
These stink bugs ought to be called chameleon bugs as their colors and patterns are so varied as to be unrecognizable.  This Bugguide page shows what a wide range of colors and patterns they present.

  James Shelton CC
"Both markings and color are highly variable, but generally includes a variably-shaped dark central band running from the head toward the rear of the insect. The pale area on the right and left sides of the pronotum contain one to three dark spots (usually two). The dark color is dark blue to black. The light color may be white, pink, yellow, orange, or red."

In addition to the wide variety of  colors and patterns, they look different in shape as they pass through their 5 instars (molts) before achieving winged adulthood.  I think that Holly's specimen is one of the late instars.

ASB on Monarch cat - Ken Christison
Lots of the ASB pictures in Bugguide and other links show them snacking on Monarch caterpillars and even Milkweed Tussock Moth larvae.  This may be a biological predilection or just that photographers like Holly like to take pictures of Monarchs and catch the incidental ASB along the way.  I suspect that they are tolerant of the milkweed toxins found in Monarch cats although I can find no studies about this.

Thanks to Master Naturalists Holly Welch and Becky Arnoldy for their photographs.
More details on the Anchor Stink Bug is at this University of Florida site.

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