Baltimore Checkerspot butterflyBaltimore Checkerspot Butterfly

Story and photos by Rose Franklin
                        (written July 13, 2001)

     The Baltimore Checkerspot is a medium sized butterfly with dazzling coloration. Named after the early American colonist George Calvert, the first Lord Baltimore (whose crest was orange and black), the Baltimore Checkerspot is mainly black with orange and white spots. Its underwings are also orange, black, and white; with these three colors arranges in a checkered-like pattern.
     The Baltimore's flight is slow and generally just above the vegetation. Like numerous other butterflies, Baltimores are poisonous to birds and they advertise their distastefulness by spreading their wings while feeding. Because they have little fear of being eaten by predators, they can often be approached closely while feeding on flower nectar.
     Baltimores are found in the north central and north eastern regions of the United States. They generally fly from around mid June through late July. Baltimores are spotty in appearance due to the spotty occurrence of Turtlehead (Chelone), the Baltimore's host plant.
     The Baltimore's life span is rather interesting. The female lays clusters of eggs (often several hundred eggs) in late July or early August. The eggs are always (as far as I know) laid on the undersides of Turtlehead leaves.
     After hatching the tiny caterpillars crawl to the top of the turtlehead and spin a communal web around the leaves they will eat. They feed as a group, overwinter as half-grown caterpillars, and then complete their life cycle the next spring.
     Being one of my favorite butterflies, I tracked the life cycle of Baltimores during the 1998-1999 season. Here is the information I compiled:
Baltimore Checkerspot butterfly laying eggsJune 25, 1998:
     At 1:30 p.m. I spotted a Baltimore Checkerspot butterfly laying eggs on the Turtlehead (Chelone lyonii) growing in our butterfly garden.
     An hour later, the Baltimore was gone but she left behind a mass of yellow eggs, approximately 150 of them. Her egg cluster is triangular in shape and only about 1/2" across. Eggs are stacked on top of eggs near the center of the egg mass.
June 29:  The eggs have turned a reddish-brown color.
July 17:  The eggs have hatched. A tiny nest is being formed at the top of the Turtlehead plant.
July 28:  There are a few caterpillars on the outside of the nest. Through the nest, I can see many more. They are about 1/4" long now.
August 28, 1998:
     The Baltimore nest has dramatically increased in size. The caterpillars have periodically enlarged their nest to encompass more Turtlehead leaves. The caterpillars are about 1/2" long now. On this warm, sunny day, many of them are crawling on the outside of the nest.
September 28:  The caterpillars are about 3/4" long. They still crawl around on the outside of the nest on warm days. Their nest has enlarged since last month, now being about 8" high and 8" wide.
The winter of 1998-1999 comes and goes. The Baltimore Checkerspot caterpillars are probably hibernating just below the surface of the soil.
May 15, 1999:
     I counted over 40 Baltimore caterpillars in the butterfly garden this afternoon. Some of them were feeding on Turtlehead but most were eating Beard Tongue (Penstemon) foliage. I saw an equal amount of caterpillars on Penstemon digitalis 'Husker Red' and Penstemon barbatus 'Prairie Dusk'. Most of the caterpillars are about 1" long.
     Some years, the Baltimore caterpillars come out of hibernation before the Turtlehead begins to grow. At these times, I'm glad I have Beard Tongue in the garden too.
June 1, 1999:  The caterpillars are about 1-1/4" long. They seem to be decreasing in number every day, probably leaving their host plants in search of a safe place for pupating.
Baltimore Checkerspot butterflyInside a butterfly pupa (chrysalis), remarkable changes occur as a caterpillar becomes a butterfly. A crawling insect transforms into a flying insect, one of the most beautiful flying insects of all. Its mouth parts change dramatically: a caterpillar chews foliage while a butterfly sips nectar with a straw like tongue (called a proboscis). Inside its pupa, it generally takes less than three weeks for the Baltimore caterpillar to become a butterfly.
June 18, 1999:
I saw two Baltimore Checkerspot butterflies in the butterfly garden this afternoon. Very bright in color, they must have just emerged from their chrysalides. As adult butterflies, Baltimores live for just a few weeks. In this short period of time, the adults will mate and then the females will lay eggs to begin the life cycle of the next generation.

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