It appears that the very late spring this year has also had an effect on the horse-chestnut leaf-miner. My impression is that the leaf mines are currently smaller than I would expect for this time of year, and few have pupated (you can tell if they have pupated by feeling the underside of the mine - there is a small bump where the caterpillar has spun a cocoon and pupated). My impression is that the size of the leaf mines is also much more variable than I would expect at this time of year. In previous years all the mines of this generation have been pupating within a day or two of each other, but this year it is a lot more variable. Will your data confirm my impression? I look forward to receiving your results via the website or the leafwatch app.
|These mines are only just beginning to form - they will probably pupate in a week or so. Photo taken on 4th July.|
|One of the few trees in south Oxfordshire that had mature mines, but it still has a lot of very small mines as well. Photo taken on 4th July.|
|This tree had very few leaf mines. Photo taken on 4th July.|