Spring is officially here, not that you needed a calendar to tell you that. Most of the country enjoyed “shorts weather” last weekend (sorry, Flagstaff AZ!), with places like northern Minnesota topping out in the 70s, nearly 40 degrees above normal. (It’s been in the mid-80s here in Central Florida – pretty darn warm for this early in the year.) This especially mild winter has caused plenty of unusual wildlife behavior, and no doubt many of you have already seen your first butterflies, in some cases weeks ahead of your normal first sightings. To get you ready for spring butterflies, here are a few common butterfly questions and answers. If you have other questions, drop me a note in the comments below.
What happens to butterflies in winter?
The answer to this question varies by species. A few species migrate or move further south, like the famous Monarch migration. But most butterflies overwinter in the same area where they spend the summer, in various forms. Some butterflies, like the Mourning Cloak, overwinter as butterflies without migrating (though some populations will head south for the winter). These butterflies seek out dry cracks in the rocks or warm tree hollows and hunker down for winter. Other butterflies, like Great Spangled Fritillaries, overwinter as caterpillars buried in the earth. And some, like Cabbage White butterflies, overwinter in chrysalis (pupa). In all cases, these creatures enter a state known as “diapause“, which is much like hibernation, in which all of their bodily functions stop until the weather warms up again. (Learn more about butterflies in winter here.)
How warm must it be for butterflies to fly?
Butterflies are “poikilotherms”, which is essentially like being cold-blooded; their body temperatures reflect the temperatures outdoors. Most butterflies need a body temperature of about 80 degrees F to fly, but it doesn’t need to be nearly that warm outside. Butterflies use solar energy to pump up their body temperature by as much as 20 degrees above the temperatures outside. So when outdoor temperatures consistently start reaching 60 degrees F or so, butterflies will begin flying.
Which butterflies appear first in spring?
This of course varies by region, but here are a few to look for as soon as days hit the 60s and 70s in your area:
- Mourning Cloaks (Nymphalis antiopa) overwinter as butterflies, and will emerge as soon as the days warm up, probably looking a little tattered and worn. They can be seen across most of the country.
- Eastern Commas (Polygonia comma) also overwinter as adult butterflies, emerging in early spring and laying eggs on the first new growth of nettles and elm trees. As the name suggests, they’re found in the eastern half of the country, except the Deep South.
- Cabbage Whites (Pieris rapae) and other members of this genus overwinter in chrysalis, making their appearance in early spring as newly-emerged butterflies. They’re seen around the country, and their caterpillars are often considered pests by vegetable farmers. (Learn more here.)
- Spring Azures (Celstrina ladon) are another butterfly species that overwinter in chrysalis and appear in early spring as newly-emerged adults. This tiny blue butterfly is found throughout the country, except in the Deep South.
What if butterflies emerge before there any plants for them to nectar on?
The “first” butterfly of spring, the Mourning Cloak, has this problem solved. It actually rarely nectars on flowers, instead preferring tree sap, which by now has been running for weeks in most places. In other cases, the earliest wildflowers of spring coincide with the first butterflies, and some of the best early nectar plants are actually flowering trees like redbuds and dogwood.
It’s also not uncommon for some butterfly species to visit hummingbird feeders when plant nectar is scarce, so fill your hummingbird feeders when butterflies start to appear to see if you can lure in a few extra visitors.
However, for some species of butterfly, these overly mild winters are a legitimate concern, especially in very warm winters like this one. Scientists are currently concerned about the effect that extremely mild temperatures can have on the Mormon Fritillary butterfly (Speyeria mormonia) - click here to learn more.
What was your first butterfly spotting of spring, and when did you see it? Share your sightings in the comments below!