Observation of the week – August 7-13, 2022

Our 13th OOTW is this Orange Sulphur, observed by new Butterfly Blitz participant Jonathan (@jcbteach). Jonathan took this beautiful picture in southern Mississauga, near Rattray Marsh.

This is the first time that we have written about the Orange Sulphur in an OOTW – although the closely related Clouded Sulphur has been featured a few times ( here, here, and here,). Both species are common and widespread in southern Ontario, and you can find both in open fields, woodland clearings, roadsides, agricultural areas, and gardens.

If you see a yellow butterfly in our area, it’s almost certainly an Orange or Clouded Sulphur. But how do you tell them apart? Orange Sulphurs can be highly variable, and it can also be difficult to differentiate between the two species without a close inspection.

Orange Sulphurs gets their common name from the patches of orange on the upper side of their wings. These patches are also a great way to tell it apart from the Clouded Sulphur. The orange flashes are easy to see while the butterfly is flying, but not when they stop to rest. This is because Orange Sulphurs normally rest with their wings closed, like most other members of their subfamily. If you can get a photo – even a blurry one – of the butterfly in flight, you can usually see the orange well enough for an identification.

Left: A blurry photo of the upper side of an Orange Sulphur’s wings, by @lltimms
Right: An Orange Sulphur resting in the usual closed wing position, note the thick black border, by @bevlynn99

Some say that the easiest way to recognize Orange Sulphurs is by their flight pattern. Orange Sulphurs have an erratic, jerky flying style and usually stay low to the ground, whereas Clouded Sulphurs have more of a “wobbly” flying style. Be warned that both species can be very strong fliers and hard to catch up to!

One last clue is the thickness of the black border seen on the upper side of the wings. This border is thicker on Orange Sulphurs than Cloudeds.

Orange Sulphurs are also known as alfalfa butterflies, or alfalfa caterpillars in their larval stage. This is because one of its major food sources is alfalfa. Orange Sulphurs are commonly found near alfalfa fields in Ontario, but rarely cause significant damage here. However, in more southern parts of their range they can be a serious pest.

Interestingly, no one is sure whether Orange Sulphurs can survive the winter in Ontario. They are usually identified as one of our breeding migrant species - those are species that move back up north each spring after dying off in the fall.

Do you want to see this gorgeous butterfly on your property? Plant native pollinator-friendly plant species such as Black-Eyed Susan, Butterfly Milkweed, Asters, Goldenrod, and Purple Coneflower. These plants will provide nectar for sulphurs and other butterfly species throughout the growing season. And then don’t forget to submit all the beautiful observations of butterflies in your yard!

Post written by Stephanie Donison, Assistant, Natural Heritage Management and Laura Timms, Senior Specialist, Natural Heritage Management

Publicado el 18 de agosto de 2022 por lltimms