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What is a California Tortoiseshell (Nymphalis californica)

California Tortoiseshell

California Tortoiseshell Overview

The California Tortoiseshell butterfly is a butterfly that mostly lives on the western side of North America with some populations of the butterfly living central and eastern United States.

These butterflies are known to have population explosions which cause massive swarms to migrate in an almost cloud-like formation of butterflies.

In 2004, a cloud of California Tortoiseshell butterflies that was 50 miles long and 15 miles wide was spotted in the Sierra Nevadas migrating south for warmer weather.

According to, if you are driving and you happen to come across a population explosion, you should try to drive under 30 mph as the slower speeds help the butterflies avoid hitting your windshield.

What is a California Tortoiseshell (Nymphalis californica)

California Tortoiseshell Butterfly, Nymphalis californica, on a Leaf


  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Lepidoptera
  • Family: Nymphalidae
  • Genus: Nymphalis
  • Species: N. californica

Size and Body Description

California Tortoiseshell Butterflies are small to medium-sized butterflies with wings that have jagged edges with greyish-white borders on them. Both their forewing and hindwing are orange and brown-orange in color with the lighter orange being near the outside and the darker orange towards the body. The front set of wings, also known as the forewings, have black spots near the top edges that continue down toward the middle of the wing. The hindwings tend to be a solid orange color with occasional spots showing up near the top of the wing.

The underside of the California Tortoiseshell butterfly is not as vibrant as the top resembling a dead leaf more than a monarch butterfly. The underside is typically brown and dark brown in color which helps them blend into trees when they are perched on branches.


California Tortoiseshell butterflies will grow to have a wingspan of around 1.25 to 2.75 inches in length from wingtip to wingtip.


California Tortoiseshell butterflies feed on a variety of flower nectar, sap, fruit, and occasionally on mud. As caterpillars, they will eat various forms of lilac.


California Tortoiseshell butterflies typically only have one wave, or brood, a year that exists from April to about May. During this time, mating and egg-laying will occur for the next brood to be hatched


California Tortoiseshell butterflies are found on the western side of the United States as well as parts of southern British Columbia and Baja California. In the United States, these butterflies live in every state west of Kansas all the way to the coast. There are small populations in Iowa, Pennsylvania, and South Dakota as well.


California Tortoiseshells are considered to have a stable population, at the time of writing this, which means that they are not currently protected by any federal laws to help their populations stabilize and grow.

References Used

California Tortoiseshell