|This question mark hasn't given up on summer. (11/2/2014, Mission TX)|
Some researchers believe that polyphenism evolved as a solution to differing needs for camouflage and thermoregulation in summer vs. winter. Perhaps summer butterflies survive better on fresh green leaves in bright coats, while fall butterflies are more comfortable with darker coloration that allows them to soak up the weak winter sun. Fall butterflies also tend to live much longer-- some late-emergent butterflies hibernate for 9 months before reproducing, instead of the brief flight window and immediate reproduction of their summer kin.
|Dainty sulphur. (11/8/14, Palo Pinto Co. TX)|
The question mark's dark morph is its summer form. In the winter, the hind wings lighten. Question marks don't typically nectar on flowers-- like the hackberry emperor, they prefer to feed on dung and rotten fruit. That's the reason you see the question mark perched on a log in the picture above- someone had smeared the log with bait. You'll notice s/he shares the perch with flies.
|Another pic of the dainty sulphur|
In white peacocks, the winter morph is larger and whiter than those which emerge in summertime. White peacock males are notable for a behavior that is somewhat unusual in the butterfly family. They defend patches of their larval host plant in hopes of monopolizing any passing females. These harmless insects perch in their small territories and engage rivals in aerial duels. I'm not sure how a 'winner' is determined. Each participant is essentially incapable of harming the other, unless it is by exhaustion.
The seasonally confused question mark looked pretty fresh, not at all like some holdover from longer days and warmer weather. I wonder if he will suffer for his poor judgement? Perhaps he pupated during a warm snap, confusing his cues. The verdict of the dainty sulphur and white peacock, and the arrival of an arctic front, tend to suggest that cooler weather is here to stay, at least for a little while.
|White peacock (11/2/2014, Mission TX)|
Wiklund, C., & Tullberg, B. S. (2004). Seasonal polyphenism and leaf mimicry in the comma butterfly. Animal Behaviour, 68(3), 621-627.
Lederhouse, R. C., Codella, S. G., Grossmueller, D. W., & Maccarone, A. D. (1992). Host plant-based territoriality in the white peacock butterfly, Anartia jatrophae (Lepidoptera: Nymphalidae). Journal of insect behavior, 5(6), 721-728.
Nylin, S. (2013). Induction of diapause and seasonal morphs in butterflies and other insects: knowns, unknowns and the challenge of integration. Physiological entomology, 38(2), 96-104.
Karlsson, B., Stjernholm, F., & Wiklund, C. (2008). Test of a developmental trade‐off in a polyphenic butterfly: direct development favours reproductive output. Functional ecology, 22(1), 121-126.