This week is a butterfly you may have seen just a few weeks ago!
Which one below is the Clouded Sulphur?
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The Clouded Sulphur is on the left!
The tell tale giveaway is the forewing color. The forewing of the Clouded Sulphur is lemon yellow to yellowish green while a splash of orange on the butterfly on the right, reveals it to be the closely related Orange Sulphur. These two species used to occupy separate ranges with Orange Sulphurs restricted to the western US but expanding alfalfa fields have brought them into contact and into hybridization. Females in particular can be difficult to differentiate. Both species are common in Vermont with the Clouded Sulphur flight period lasting slightly longer (May to November) than the Orange Sulphur (June to November).
If you break out your UV flashlight, you can find an additional ID characteristic - male Orange Sulphurs display UV coloration on their forewings. You can read more about the research behind this display here.
Ready for the new quiz? Head over to Week 3 to test your habitat and butterfly ID skills!
Orange Sulphur by Stan Runnels (iNaturalist)
Clouded Sulphur by Jeff Cherry (iNaturalist)
These hybridize quite a bit and I wonder if that one on the left has a wee bit Orange Sulphur genes? Do I see just a wash or splash of orange there on that hindwing? Cool about the UV light! I might have to take my moth light and shine on one next year!
