The Painted Lady (Vanessa cardui) is probably the most spread butterfly across the world. Hence, these tips to find caterpillars of it should work for anyone living within the habitat of the Painted Lady.
Step 1: Track down time and location
During the wrong time or at a false location searching for caterpillars will result in guaranteed failure. When nothing’s around there’s nothing (besides possibly other species) that can be found.
The Painted Lady is a migrating species, spending the winter in the South where the climate is more suitable. Individuals head North during spring and settle for breeding. The first Painted Ladies flying around are a good indication there will be eggs and caterpillars soon. For example, this summer the 2nd Red Admiral (Vanessa atalanta) that I spotted was already laying eggs. That butterfly, another migrating species, shares a lot of habits with the Painted Lady.
Step 2: Track down the food plant
Once the time and location are right, you’ll have to go further down in finding the needle in the haystack. In case of the Painted Lady the needle are thistles, and the haystack is the habitat where you’ve sighted the butterflies flying. See the photos below for two sample habitats where I got lucky.
Step 3: Track down the plant that got laid on
This might be the tricky step. Sometimes it’s rather easy to find dozens of eggs or caterpillars. And sometimes, there’s none. Believe me, I’ve often come home with an empty jar. Nevertheless, start browsing. Eggs are mostly laid on spots with direct sunlight. Therefor, don’t waste your time checking places in the shadow.
Regarding on how far the cycle of metamorphosis has progressed, you’ll either find eggs or caterpillars. The size of the caterpillars can vary from 2 mm to about 4cm. Of course you might also spot a chrysalis. Below are some shots giving hints on what you can expect to find on the leafs on thistles.
Step 4: Start raising the caterpillars
In case you get lucky and find either eggs or tiny caterpillars here’s another good tip. For the Painted Lady I personally feel it’s easier to feed them with nettles (nettles don’t wither that easy as e.g. thistles do). Cut a small top piece of a nettle and place it in a box. Place the eggs or caterpillars in the same box (make sure the little ones will find their feast).
Spray a little water over the plant and seal the box. It’s ok keeping the box completely sealed and airtight. The box generates a micro climate which keeps the plant easier alive, and caterpillars won’t suffocate if you open the box every day or two for cleaning.
The nettle below hosts a dozen caterpillars of the Painted Lady. The black spots are webs and excrement by the larva. Once they have grown I’ll place them in a terrarium with more space and where observing the caterpillars will be easier.
One more tip: Family fun
Last but not least, searching caterpillars is an activity for the entire family if you wish so. While I was out searching for the eggs and caterpillars shown in this post I had our twin toddlers in the stroller with me. Just 1.5 weeks earlier, me and our daughter were chasing a Painted Lady on it’s egg laying flight.