In October it starts getting difficult to find caterpillars in the wild. This time of the year I usually take a lazier approach and visit the allotment gardens located nearby. There’s still plenty of food plants attracting butterflies to lay eggs on, and particularly the Large White (Pieris brassicae) and the Small White (Pieris rapae) are species that can be found.
Both species commonly migrate to Finland from South in late summer. In 2015 I found masses of Large White caterpillars. Early October this year, it was primarily Small White caterpillars. These are more difficult to spot, but due to the feeding traces it’s easy to know when they’re around.
While there was caterpillars on different instars also eggs could still be found. Here’s some photos. The yellow line on the back is a clear indication for determining the species. The Green-veined White (Pieris napi), the most common of the Whites in the region, has in general a caterpillar that looks pretty similar.