Elfin butterfly (Callophrys sp.) typically emerge during early to mid April locally as I posted recently. This year that schedule is running late. I have had few spring sightings, only one Brown Elfin and one Western Pine Elfin. Weather locally has been described as…
After a winter of cold-weather records, Missoula’s spring still appears stuck somewhere between “brrr” and “yuck.”
Statistics from the National Weather Service show this April was the fourth-wettest on record, and caps a first quarter of 2019 with the coldest start since 1979. The average daily temperature from January 1 to April 30 was 27.3, which hasn’t been matched in 40 years.
Rob Chaney of the Missoulian – Frigid April caps chilly start to 2019
Comma and Tortoiseshell butterfly dominate early spring sightings over most of the U.S. because they overwinter as adults. As soon as climatic conditions are appropriate, these butterflies are flying around seeking out nectar, moist soil and each other. Other species have different strategies. They overwinter as an egg, caterpillar or pupa.
Elfin butterfly go through winter as a pupa. That is the final stage in which a caterpillar morphs into a winged insect. But there is a spectrum of internal pupa development among butterfly species. For Elfins, the adult butterfly is almost fully formed inside the pupa that overwinters. When climatic conditions in the spring meet biological requirements, the pupa begins eclosion. Eclosion is the technical term for adult butterfly emergence from the pupa.
Weather forecast for the balance of the first week in May is expected to be normal for temperature with plenty of sunshine, good for eclosion! I plan on taking advantage of the conditions and will be looking extensively for these small butterflies. Below is a composite of the four adult Elfin butterfly species that I will be looking for.
