As the weather cools, insects are scarcer. However, our mild winters mean we still see them roam our neighborhood parks and preserves year-round, and this is especially true for butterflies.
Sure, their numbers are slim, but they take full advantage of our fall and winter blooming plants. The Painted Lady (Vanessa cardui) is no exception and still visits Mission Trails during the winter as seen in this observation by docprt on iNaturalist: inaturalist.org/observations/52589759.
The Painted Lady is the most common butterfly species on the planet, found everywhere except in Australia and Antarctica. Despite that, I realized I didn’t know much about these beautiful orange, black and white butterflies. So, I set out to learn more about these amazing creatures.
We tend to think about butterflies as fragile creatures, but they are remarkably strong.
In fact, the Painted Lady is strong enough to handle migration journeys of over 100 miles per day, sometimes flying as fast as 30 miles per hour. It will stop frequently to feed on nectar for energy. It is not picky about what plant to sip from and has been recorded feeding from over 300 plant species. It is not particular about what plant to lay its eggs on either with over 100 different species on the list of hosts for the caterpillars. However, the Painted Lady seems to have a very strong preference for thistles (genus Cirsium) and is often found around these plants.
Males, who by the way are very secure in their masculinity and do not mind at all being called “ladies”, are very territorial and will wait for females to stop by and mate. The female will then lay up to 500 delicate pin-head-sized green eggs, one at a time, on various plants. It will take about one week for an egg to hatch, and the small caterpillar will start munching away on the leaves.
As it grows, it will build shelters, wrapping the leaves of the plants with silk spun from a spinneret located below its mouth. These shelters are perfect for the caterpillar to feast while being protected from predators. As the little beast grows, it will molt about four times and change appearance in the process. When they reach about 4 inches in length, they will enter the chrysalis stage and finally emerge as an adult within a week or two.
The adult Painted lady will then travel again, continuing on the multi-generational migration route. It will live for another two to four weeks and repeat the procreation cycle again. The offspring of the second generation might continue the route or head back in the other direction depending on the time of year or weather.
Painted ladies are not your usual seasonal migrants. Instead of strictly following seasons, they seem to be following weather events such as El Niño. In rainy years, they have been seen migrating through San Diego by the tens of thousands. In drier years, the migration patterns are hardly noticeable.
According to iNaturalist data, Painted Ladies in San Diego are most often seen in March and April, but also experience a second peak from September to November. They are observed least frequently during the month of July.
Photo by Peter R. Thomas
– Patricia Simpson is a trail guide at Mission Trails Regional Park.
