Whirlabout (Polites vibex) life history
Whirlabout (Polites vibex) Life History


Egg, 5-29-10

Head visible, 6-2-10
         

6-3-10
     

6-9-10
     

6-23-10
     

6-27-10
     

7-3-10
     

Mature caterpillar, 7-16-10
     

Chrysalis, 7-24-10 (formed ca. 7-18-10)
     

Fresh female adult Whirlabout, 7-26-10
 

Sometimes one is just blessed to be at the right place at the right time. One fine day in May, 2010, I was on my knees looking for butterfly eggs on a low-growing weed. I found none, but as I was searching, a female Whirlabout landed on a clump of grass about a foot in front of me. As I watched, she moved around a bit, crawled down into the clump, deposited an egg, and then went on her merry way. I collected the egg to raise.

I was scheduled to leave town in a couple of weeks, and I didn't expect to be able to complete the study before leaving. So I planted some of the grass, an unidentified native species, in a flower pot. When it came time to leave, I released the caterpillar into the pot and left the pot on the porch. The caterpillar could have wandered away; it could have been eaten by a spider or other predator; or, it could hide itself so well I wouldn't be able to relocate it. To my pleasant surprise, upon my return I easily found the caterpillar and was able to resume the study.

The caterpillar was now three weeks old, and it still had a nondescript black head and green, freckled body. This soon changed; with the next molt two light stripes on the face appeared (6-27-10); in later instars, other markings became apparent and the head was primarily a bronze color. The body, meanwhile, developed tan bands that gradually grew together.


Whirlabout caterpillar face

Throughout its stages, the caterpillar formed a nest by sewing together several blades of grass. There was a white powdery substance on the webbing after the chrysalis was formed.

The caterpillar took 6 weeks (42 days) to pupate; the adult emerged just over a week later. The entire cycle from egg to adult took almost 8 full weeks.

In late June, I found a caterpillar on Guinea grass (Panicum maximum) that also proved to be a Whirlabout. This caterpillar appeared to be a first instar (and so almost 3 weeks younger), yet it pupated and emerged on the same dates as the caterpillar raised from the egg. 

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