Just a couple days ago I came across the first caterpillars this spring. This has been a good sign to see how far nature’s cycle has progressed, and gave green light to start looking for keepers.
I’ve set myself 11 targets for this season. By targets, I’m referring to species from which I’ll particularly try to find caterpillars and raise these all the way to the adult butterfly. Time to kick-off the caterpillar quest.
Today, I made a first attempt. There wasn’t that much around yet. I found three colonies of Small Tortoiseshell (Aglais urticae) caterpillars. In one case the caterpillars just hatched. The small size of these caterpillars indicated it may be too early to look for other species. They may not have hatched yet, or are simply too small to be found.
While I also came across a construction site where my favorite biotope is being bulldozed I checked if there’s any Alder Buckthorn (Rhamnus frangula) around. Alder Buckthorn is the food plant of the Common Brimstone (Gonepteryx rhamni). The caterpillars were pretty small, but since that piece of forest will be turned over soon, I decided to grab some with me.
Bottom line, with the Common Brimstone caterpillars the first target is accomplished. And there’s finally some life in the terrarium.
Forest with Alder Buckthorn and where caterpillars of the Common Brimstone were found
Alder Buckthorn, the food plant of Common Brimstone caterpillars
Forest turning into a construction site
Caterpillar of the Common Brimstone in breeding cage
Alder buckthorn and Common Brimstone caterpillars placed in a terrarium (top). The bottom terrarium hosts a chrysalis of the Old World Swallowtail (Papilio machaon) and the cocoon of a Poplar Hawk-moth (Laothoe populi)
Colony of young caterpillars of the Small Tortoiseshell
Recently hatched caterpillars of the Small Tortoiseshell
Caterpillars of the Small Tortoiseshell
March 1st, this year spring arrived early in Finland and nearly all snow was gone already by the end of February. A sunny Saturday with +0.5 degrees Celsius sounded like a good day to kick start into the butterfly season.
Almost a month ago my dad, living in Switzerland, reported his first butterfly sighting, a Common Brimstone (Gonepteryx rhamni). In Finland, the waiting continues. A realistic average expectation to observe the first flight of a butterfly is probably April. However, I couldn’t hold myself back to give it a try. The first attempt to score one of the season targets was focusing on a real challenge, finding small Purple Emperor (Apatura iris) caterpillars which overwinter in the stage of larva.
Let me keep the results short: I failed. Despite of the proper preparation, including research on the web finding the right field plus cycling a total of 20 km to reach a promising spot. The major problem turned out to be scanning the surrounding and detect the right food plant. Having no leafs on trees this time of the year, my botanical skills were not sufficient to sight a goat willow (Salix caprea) at a promising location, which then may or may not host any of these tiny caterpillars.
I had to accept my defeat, and decided to give it another try when the temperature is more comfortable, or perhaps when the trees wear leafs again later in spring. It will not only be easier to detect the right bush or tree, but traces on these leafs can help finding a spot where caterpillars have been feeding.
All in all, it feels great knowing that winter has almost passed, and the entire season is ahead. Furthermore, to highlight at least one positive sake of this first caterpillar quest: I got some sports spending time on the mountain bike.
Details and information on the Purple Emperor are provided by The Purple Empire, a blog dedicated to this particular species. It contains a collection of great photography and insights into the world of this beautiful butterfly.