Invertebrates
Clouded Sulphur
Colias philodice · also called clouded sulphurs, common sulphur
Along a roadside patch of clover, dozens of clouded sulphurs gather at a damp puddle, a common sight across nearly all of North America and one of the most frequently encountered butterflies most people will ever see without realising it.
Overview
The clouded sulphur, Colias philodice, is a small, pale yellow butterfly native to fields, roadsides, and agricultural land across a broad range spanning nearly all of North America. Its status as one of the most commonly encountered butterflies on the continent, habit of gathering in groups at mud puddles, and tendency to hybridise with the closely related orange sulphur make it one of the most familiar, if often overlooked, butterflies across North America.
A butterfly hiding in plain sight
Common enough to blend into the background of everyday roadsides and fields, the clouded sulphur is one of those butterflies most people have seen countless times without ever stopping to notice it specifically.
Status
Least Concern — widespread and abundant across suitable open habitat throughout nearly all of North America.
Clouded Sulphur: common questions
Why do clouded sulphurs gather in groups at mud puddles?
This species frequently gathers in groups at mud puddles, damp soil, and other moist ground, a behaviour known as puddling that helps the butterflies obtain salts and minerals they cannot get from nectar alone, and large gatherings of this and other sulphur species are sometimes what gives rise to the nickname of a sulphur cloud.
How is the clouded sulphur different from the cloudless sulphur?
Despite the similar name, this species is smaller and displays pale yellow wings with a dark border, quite different from the larger, more uniformly bright lemon-yellow appearance of the cloudless sulphur, and the two also differ in typical size and some behavioural details such as migration tendency.
Does the clouded sulphur hybridise with other butterflies?
Yes, this species readily hybridises with the closely related orange sulphur where their ranges overlap, producing individuals with intermediate colouration between the two parent species, a genetic mixing common enough that it can genuinely complicate identification in areas where both species are present.
Why is the clouded sulphur so commonly seen?
This species produces several generations within a single growing season across much of its range and feeds on widely available host plants such as clover and alfalfa, a combination that allows populations to build up considerably and remain common across fields, roadsides, and agricultural land throughout nearly all of North America.