Mexico, USA & Canada
Family - PIERIDAE
subfamily - COLIADINAE
Colias philodice female, New York, USA ©
There are over 80 species of
Colias worldwide, of which the majority
are inhabitants of temperate grasslands or sub-arctic tundra. In
South America there are 5 species found on the Andean paramo and
puna grasslands. There are 18 species in North America, two of which
also occur in Central America; and there is one species endemic to
Colias species are migratory in
behaviour. Some simply move up and down mountainsides as the seasons
advance, to take advantage of fresh growth of their larval
foodplants and adult nectar sources. Others undertake much longer
migrations - e.g. Colias crocea, which
migrates annually from North Africa to northern Europe.
Colias are collectively known as
Sulphurs in North America, but elsewhere in the world they are
called Clouded Yellows. On the upper surface of the wings the ground
colour varies from pure white to deep orange according to species,
but the majority are some shade of yellow. Males of most species
have narrow black wing borders. In females the borders are much
wider, and the ground colour is always paler.
Colias philodice is distributed from
Alaska and western Canada, to Guatemala.
Colias philodice male, Tennessee, USA ©
This species, due
to it's migratory behaviour, can be found in almost any habitat
within it's range, but is most abundant in
Medicago ( alfalfa ) fields.
The eggs are cream
coloured when first laid, but soon turn crimson as the larva
develops within. They are laid singly or in two's and three's on the
leaflets of Leguminosae including Astragalus,
Trifolium and Vicia. The fully
grown larva is green, with a faint mid-dorsal line. There is a white
lateral line, with a pinkish line running through it, and a series
of black dashes beneath it. The caterpillars hibernate overwinter
when in the 3rd or 4th instar.
Males of all
Colias species have a distinctive cycle
of behaviour - they patrol back and forth over the breeding sites in
search of females, for several minutes at a time, and then suddenly
swoop down and settle on bare soil. There they remain for several
more minutes, even in hot sunny conditions when they would be
expected to continue flying. After resting for a while, they take
flight again, but instead of patrolling for females, they fly from
flower to flower, nectaring for a few seconds before moving on to
the next. They then undergo another period of rest, before resuming
their search for a mate.
mating, follow a different cycle of behaviour. They typically spend
several minutes nectaring, then rest for a while, and then go on an
egg-laying run, during which they fly rapidly back and forth across
the breeding site, stopping here and there for a moment to glue an
egg to a leaf. They then have a rest and recovery period of about 15
minutes before repeating the cycle.