Vanessa cardui is a member of the order Lepidoptera and the family Nymphalidae, which is the most diverse family of butterflies. This family is also called brush-footed butterflies because the forelegs of these butterflies are very small and covered with hair. V. cardui is the most widely distributed butterfly in the world. It can be found in North America, Africa, Europe, and Asia. In North America, the Painted Lady is seen in most of the fifty states and Canada, the range reaching as far north as the Arctic Circle. The upper surface of the Painted Lady is orange and brown. The front wings also have white spots, while the hindwings each have four small eyespots underneath.
A fascinating characteristic of butterflies is their complete metamorphosis, which is the process of growth and development where an egg hatches into a larva, the larva transforms into a pupa, and the pupa emerges into an adult. When the larvae emerge, they will eat more than their body weight each day. Painted Lady larvae usually feed on plants from the Malvaceae and Compositae families. The larva grows and expands through one molt, and then continues to grow until it becomes a pupa, which is also known as a chrysalis. Although the chrysalis may appear inactive, it is undergoing a rapid transformation into an adult butterfly. When the transformation is complete, the butterfly emerges from the chrysalis. At first the wings will be folded or crumpled; however, the butterfly will soon begin to pump its wings, forcing fluid from the abdomen into the veins to inflate the wings to the proper size and shape. After a couple of hours, the butterfly will be ready to take flight.
When you receive your caterpillars (larvae), place the container upright and out of direct sunlight in an area where it can be easily viewed. Ideally, the caterpillars should be kept at a temperature between 21–27°C (70 – 80°F), but they can tolerate a range as wide as 18 – 29°C (65 – 85°F) and still develop normally. The rate of their development is dependent on the temperature of their surroundings; the cooler the temperature, the slower they develop and the warmer the temperature, the faster they develop.
The caterpillars will grow quite rapidly, producing a silky material that helps them to move around the container and provides shelter in their natural environment. If condensation forms inside the plastic container, wipe the excess water off with a paper towel. The caterpillars will excrete waste that looks like greenish brown balls. It is not necessary to remove the waste from the container at this time; however, if you prefer the waste may be scooped out with a clean spoon. Periodically, the caterpillars may appear lifeless during the growing period. This is normal and usually indicates that the caterpillar will be molting soon. When the caterpillars are fully grown, they will stop feeding, climb to the top of the container, and hang down, head first. At this time, they will shed their outer skin, revealing a chrysalis.
When all of the caterpillars have reached this pupal stage or are hanging down, head first, carefully remove the lid and tape the paper lining with the chrysalides to the inner side of a box or cage suitable for housing and viewing butterflies. Do not leave them in the original container. If any of the chrysalides fall, gently wipe off any debris and hang the fallen chrysalides by attaching the small pointed protrusion of the chrysalis to a cotton ball and then taping the cotton ball to the wall of the cage. By hanging the chrysalides, the wings of the butterflies will have a better chance of developing normally. It is very important not to puncture or squeeze the pupae during this procedure and the use of insect forceps is highly recommended. If it is impossible to hang the chrysalides, gently set them on the bottom of the cage or box.
In 7 –10 days the butterflies will emerge and, after a short period of pumping up their wings, will be ready to fly. During this time, the new butterflies may excrete a red liquid called meconium, which is a built-up waste from the pupal stage. Feed the butterflies by wetting a piece of cotton or paper towel in a solution of two teaspoons sugar, brown sugar, or honey mixed with one cup of water. The butterflies can then be released or kept in their cage for the entirety of their two or three week adult life span.
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