A bright yellow Clouded Sulphur butterfly sipping nectar from a purple flower. Colias philodice.

Wild Facts About The Clouded Sulphur Butterfly

ByChristine Wild Animals
Clouded Sulphur Butterfly. Colias philodice. Yellow butterfly. Insect. Photograph taken by the author. Copyright © 2024 Now I Wonder. All rights reserved.
Clouded Sulphur Butterfly Colias philodice Yellow butterfly Insect Photograph taken by the author Copyright © 2024 Now I Wonder All rights reserved

How To Identify Clouded Sulphur Butterflies

  • Clouded Sulphur Butterflies have wingspans of 1.4 – 2.0 inches (3.6 – 5.0 cm).
  • They can be hard to identify for two reasons:
    • Males and females look different (this is called sexual dimorphism),
    • Their appearance changes with the seasons (called seasonal variation); spring and fall individuals look slightly different from summer butterflies.

Appearance Of Spring and Fall Clouded Sulphur Butterflies

  • Spring and fall adult Clouded Sulphur butterflies are:
    • Smaller
    • Greenish-yellow in color (Pyle 1981).

Appearance Of Summer Clouded Sulphur Butterflies

  • Summer Clouded Sulphur Butterflies are:
    • Larger
    • Bright yellow

Wing Features (Top View)

  • Males are bright, sulphur yellow with distinct, solid black wing borders.
  • Females are yellow or white with black wing borders that have yellow spots.
  • Both sexes have a black spot on the forewing and an orange spot in the center of the hind wing.

Wing Features (Bottom View)

  • Green-yellow with a faint row of dark spots.
  • Males have one black spot in each forewing.
  • Female may have a small, pinkish wing spot on each forewing.
  • The hind wings show two silvery spots (one large, one small), each thinly rimmed in red.
  • Thin edge of pink fringe on the wings and a row of tiny brown spots on the hind wings.
  • These butterflies almost always close their wings when they land, so you’re more likely to see the underside of their wings than the top.

Appearance Of Clouded Sulphur Butterfly Caterpillars

  • Clouded Sulphur caterpillars are bright green, with a white stripe down the side.
    • The stripe may have tiny pink or orange spots, and a dark green or black bottom edge.
    • Their heads are round and bright green.

Where And When To Find Clouded Sulphurs

Adult Clouded Sulphur Butterflies

  • Clouded Sulphur butterflies live throughout the eastern United States, although they are far less common in Florida.
  • Adults fly from late March to mid-November in most of their range. Females lay eggs throughout the warm months, so new generations appear often.
  • Look for Clouded Sulphur Butterflies anywhere lots of flowers bloom, especially:
    • Meadows
    • Roadsides and along ditches
    • Farm fields
    • Power line cuts
  • These butterflies prefer open, sunny spaces and avoid deep forests.
    • Clouded Sulphur Butterflies especially like places where clovers, vetch, and other legumes grow.

Clouded Sulphur Caterpillars

  • Look for Clouded Sulphur caterpillars anywhere plants in the Legume family grow, especially in:
    • Meadows
    • Fields and pastures
    • Roadsides
    • Power line cuts
    • Waste lots
  • Clouded Sulphur butterflies are generalists; they can live, find food, mate, and lay their eggs in a variety of habitats..
    • They also tolerate habitats that humans have disturbed, like roadsides, power line cuts, and farm fields.
    • As a result, they are both widely distributed and abundant.
      • Clouded Sulphur butterflies were the most abundant species observed in a study that researched pollinator populations in different Iowa agricultural fields.
Clouded Sulphur Butterfly. Colias philodice. Yellow butterfly. Insect. Photograph taken by the author. Copyright © 2024 Now I Wonder. All rights reserved.
Clouded Sulphur Butterfly Colias philodice Yellow butterfly Insect Photograph taken by the author Copyright © 2024 Now I Wonder All rights reserved

Clouded Sulphur Butterflies Vs. Orange Sulphur Butterflies

  • Clouded Sulphur Butterflies are closely related to another Colias species, the Orange Sulphur Butterfly (Colias eurytheme).
    • The two species look almost the same, live in the same areas, and eat many of the same food plants.
    • Sometimes the two species mate (Opler and Malikul 1992).
  • Humans often struggle to tell them apart—but butterflies experience no such difficulty.
    • Male Clouded Sulphur Butterflies give off special smells called pheromones, which female Clouded Sulphurs use to find conspecific (same species) mates.
    • Orange Sulphur Butterflies don’t make the same smells, so individuals of each species can differentiate between conspecific and heterospecific (different species) butterflies (Grula et al. 1980, https://doi.org/10.1007/BF00987543).

What Do Clouded Sulphurs Eat?

Adult Clouded Sulphur Butterfly Food

  • Adult Clouded Sulphur butterflies eat flower nectar.
  • Favorite nectar sources include:
    • Blue Vetch (Vicia cracca)
    • Wild Lupine (Lupinus perennis)
    • White Sweet Clover (Melilotus alba)
    • Red Clover (Trifolium pratense)

Clouded Sulphur Caterpillar Food

  • Clouded Sulphur caterpillars eat the leaves of a wide variety of plants, but especially like plants in the Legume family Fabaceae.
  • These include:
    • Alfalfa (Medicago sativa)
    • White Clover (Trifolium repens)
    • Birdsfoot Trefoil (Lotus corniculatus)
    • Blue Vetch (Vicia cracca)

Why The Love For Legumes?

  • Clouded Sulphur butterflies and their caterpillars thrive on lots of different plants but especially rely on plants in the Legume family Fabaceae (sometimes also called the Pea family, the Bean family, or Leguminosae).
  • Legumes are special plants that are supported by nitrogen-fixing bacteria.
    • Nitrogen (along with carbon and the ratio between the two) is absolutely essential for plant growth, and thus the growth of any animal that eats the plants.
  • Plants with nitrogen-fixing bacteria can respond better and more efficiently to changing environmental conditions, like increased carbon dioxide in the atmosphere, than plants without bacterial support.
    • This helps legumes maintain the kind of carbon-to-nitrogen balance that supports good nutrition.
  • Because they feed on legumes, Clouded Sulphur caterpillars can still grow well when carbon dioxide levels are high, and can grow better than other insects that rely on non-legume plants for food.

Scientific Classification

  • The common name for this butterfly species can be spelled with either a “ph” or an “f”.
    • The International Union of Pure and Applied Chemistry (IUPAC) made “sulfur” the preferred spelling in 1990, but many books and field guides still use the old spelling.
    • Either one can be considered correct spelling for this butterfly’s common name.

Kingdom

Animalia (animals)

Phylum

Arthropoda (arthropods)

Class

Insecta (insects)

Order

Lepidoptera (butterflies and moths)

Family

Pieridae (whites and sulphur butterflies)

Genus

Colias

Species

C. philodice

Scientific Name

Colias philodice

Clouded Sulphur Butterfly Photo Gallery

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Christine
Christine is the creator and author of NowIWonder.com, a website dedicated to the animals and plants that share our world, and the science that helps us understand them. Inspired by lifelong exploration and learning, Christine loves to share her knowledge with others who want to connect with wild faces and wild spaces.
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