The smallest butterfly in the USA, the tiny western pygmy blue (Brephidium exile) is notoriously difficult to find, but is certainly worth searching for as it is beautifully patterned with delicate markings (3). The wings of this alluring butterfly are copper brown, marked with dull blue on the upper-sides, and flecked with white on the underside of the hindwings. The wings are also fringed with white, and there is a row of black spots on both the outer margin and near to the base. The western pygmy blue begins life as a yellow-green caterpillar spotted with tiny brown tubercles(4)(5).
Between May and November, the male western pygmy blue defends a small territory, and spends much of its time searching for receptive females. After mating, the female western pygmy blue lays the eggs on the leaves of a saltbush species (Atriplex spp.) (2). The eggs hatch into caterpillars which form a symbiotic relationship with ants (Iridomyrmex species), for which the caterpillar provides food in the form of a nectar liquid whilst gaining protection from the ants in return (6)(7). Once the caterpillar is fully grown, it will pupate to form a loose cocoon, and then undergoes metamorphosis before emerging as an adult butterfly (8).
A weak flier, the western pygmy blue flies close to the ground, and is restricted by its short proboscis to collect the nectar from small flowers. The caterpillar feeds on all parts of the host plant (3).
Having a pH greater than 7.0. Soil is regarded as alkaline if it has a pH between 8.0 and 10.0. Alkaline soils are usually rich in calcium ions.
A sheath of silk, which is spun around the pupae of some insects (a pupa is a stage in an insect’s development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis).
An abrupt physical change from the larval to the adult form.
A tubular protrusion from the anterior of an animal (e.g. the trunk
of an elephant).
The process of forming a pupa, the stage in an insect’s development when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
Relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
An area occupied and defended by an animal, a pair of animals or a colony.
A small, rounded, wart-like bump on the skin or on a bone.
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