Cabbage butterflies becoming common
Lately, I’ve been noticing the cabbage butterfly, which is the small white butterfly, with black markings. Since many insects are named after the plants they feed on, I always assumed these butterflies fed heavily on cabbage plants.
A female cabbage butterfly has two black dots on its forewings, while the male has only one dot. I read, somewhere that this butterfly has ultraviolet colors that are invisible to us. The males use their flashing wings as a way of telling males from females.
The cabbage white is said to be the most widespread butterfly in the United States. Its scientific name is Pieris rapae. These butterflies can migrate over a distance of one hundred miles, with flights beginning in early spring and continuing through September.
In North America, this butterfly reproduces throughout the summer. It is one of the first butterflies to emerge from its chrysalis in the spring and can be seen until the first hard freeze in the fall. The cabbage butterfly is another species which was accidentally introduced to this continent from Europe. Its correct name is the European Cabbage Butterfly. After being accidentally introduced near Quebec, Canada, in 1860, this butterfly crossed the border into the United States eight years later.
During the course of a summer, three generations are born in our area, and in the southern states, reproduction can create as many as five generations.
Within two to three days of emergence from their chrysalis, mating ensues. These butterflies couple tail to tail for many minutes to allow the passing of sperm packets to transfer from the male to the female. After spotting a female, the male continues to fly, zigzagging up and down in front of her until she lands. The male flutters and catches her closed forewings with his legs; he spreads his wings, causing her to lean over. Usually, the male flies a short distance with the female dangling beneath him. An unreceptive female could fly vertically or spread her wings and raise her abdomen to reject the male.
The life cycle of the butterfly continues when hours later the female butterfly deposits tiny eggs onto the undersides of Brassica leaves, such as mustard, wild radish, pepperwort and many others in the crucifers and related plants. She could lay several hundred eggs, which are a bright orange-yellow color, all arranged in straight rows known as slabs.
Hatching takes place in one week, with the rows of eggs all hatching at the same time. After the caterpillar inside the egg chews its way out, the egg shell is eaten. Naturalists believe this enables the caterpillar to immediately make the silk needed to keep the caterpillar from slipping on the waxed surface of the plants.
Most host plants of the cabbage butterfly contain mustard oils that allow the females to locate plants on which to deposit their eggs.
The female lays her eggs on the nasturtium plant, although it is not related to the cabbage family; however, the nasturtium gives off the same pungent oil that smells exactly as the oil contained in the cabbage plant.
One day I watched as several pairs of cabbage butterflies flitted about the garden. These butterflies are nectar-drinkers, and, in our yard, they seem to prefer a little blue flower (lobelia) my wife has planted in the window boxes. I was able to catch a female to examine under a 10X hand lens. On close examination, I found the female to be quite homely, with long hairs covering her body; slender antennas, with knobs on the ends; large compound eyes and wings that appeared to be white, flecked with both tiny black dots and large black dots. I noticed my fingers were coated with a fine dust that was presumably from the body.
After the caterpillar goes through a molt and changes color, a rest of three or four days is needed. Then, the caterpillar begins to eat both day and night, causing a great amount of damage to a cabbage patch.
In early days, a stake attached to a horse’s skull, which had been bleached white from the sun, was driven into the ground (a mare’s skull was preferred over a stallion’s) to attract these butterflies, by the whiteness of the skull, to lay their eggs. Later, egg shells were used in place of the skull. If the eggs were laid either place, they would receive no protection and be broiled by the sun. If by chance they did hatch out, the caterpillars would find no nourishment and die.
After feeding for about one month, the caterpillar will strap itself to some support and turn into a chrysalis. The whole process will be repeated once the butterfly emerges.