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Migration of Caterpillars in California

In California there are 225 species of butterfly; 170 of them have ranges in Southern California, which has the warmth and food needed by the butterfly larva, or caterpillars. Besides 225 species that migrate throughout California, hundreds of subspecies exist. Most caterpillars that migrate through California do so for a food or plant that is plentiful in the state.

  1. Monarch Caterpillars

    • The monarch is one of the state's larger butterflies and recognized for its orange color and veins outlined in black. It wings are bordered in black and there are white spots within the black borders. The monarch likes moister areas of California and has been found to travel from Canada to Mexico. The Monarch caterpillars feed on milkweed, which is plentiful in Southern California. In areas where there is an abundance of milkweed there is also an abundance of monarchs. The monarch butterfly has relatives like the painted lady that are similar.

    Recognizable Caterpillars

    • The swallowtail butterfly, also a large species, has been recorded in California for decades. Experts suspect that the some swallowtail species recorded as being present in Southern California are subspecies: either philenor from Arizona or hirsute from Northern California. The swallowtail is mostly black with orange spots and iridescent blue markings on its wings. Their appearance is different in California than other states. The caterpillar's food plant is Aristolochia californica, an ornamental vine known as the pipevine, which is plentiful at the Rancho Santa Ana Botanic Garden.

    Agricultural Caterpillars

    • Some butterflies frequent crops, which are abundant in California. Orange sulphur butterflies are common in California because of the state's alfalfa fields. The orange sulphur butterfly is yellow and orange; the border on the wing of the male is darker and more solid than on the female. The caterpillar (known as alfalfa caterpillar) is found in the lowlands and valleys of California where there are a lot of alfalfa farms. In areas where alfalfa production has waned, the orange sulphur population has also gone down. The caterpillar eats primarily alfalfa, but also legumes and deerweed. In the Mt. Pinos region and the Santa Ana Mountains it consumes Lotus crassifolius.

    Higher Altitude Caterpillars

    • In mountainous areas in the state, caterpillars of butterflies such as Gabb's Checkerspots that have a food supply at higher altitudes are more likely to be found in the California mountains. These orange and yellow butterflies have white checkering on their wings. The caterpillars eat Corethrogyne filaginifolia in the Santa Ana Mountains, a plant reported on Santiago Peak at an elevation of 5,687 feet. They also feed on Haplopappus squarrosus and Heterotheca grandiflora. The caterpillar may be more common in the Lagunas and San Joaquin Hills.

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