It’s an interesting question and I don’t think there’s a good answer.
I would say that in comparison with the distant past, the hatches of all the flies are not on par. In that I agree with Ivor. I can remember much larger March Brown and Olive hatches and more iron blues when I was younger, however I have witnessed very large March Brown and Dark Olive hatches in recent years and during lockdown there was the biggest hawthorn fall I’ve ever witnessed.
So Onto this year . So far I would say on the Don it has been fairly average for recent years. There was big LDO hatches back in late Feb/early March before the season started and they have continued to trickle off everyday but in small numbers so they are easily missed.
The March browns appeared late March and there were good hatches the second week of April which is later than usual. They were the classic 1hr window but it could be anytime from 10am to 3pm depending on the weather and that is different to how it was 30 years ago when you could almost set your watch by them at 12 noon. They were sparse but significant enough before and after that week to get the fish feeding.
The Olive uprights have not appeared in the numbers we are used to these days and they are mostly smaller than they normally are, they have also been scattered small bursts over a 6 hour period rather than a sustained and obvious hatch.
I’ve not seen any iron blues yet but there are Brook Duns coming off in their usual here and there appearances. They rarely cause a rise.
This last week there have been some huge Grannom hatches where I’ve been, along with some smaller sedges in amongst them. This has had the fish feeding on the pupa and a few of the adults, but when they were hatching there were hundreds of them every time the sun came out. This appeared fairly normal to me, except it’s about 2weeks late. When they came off I could literally see dozens of shucks and hatching sedge all round be in the river.
I saw the first yellow mays starting on Saturday during the afternoon and that’s about normal but it remains to be seen how that goes.
Last year the blue winged olive hatch was quite poor on an evening but the bigger sedges were quite normal.
So I guess the main thing I’ve noticed is that a lot of the flies are smaller than usual and are definitely less prolific than decades ago but for the last 10 years things are much the same regarding quantity but the timings are all over the place and predicting when to hit it has been tough. When I have been out and hit the window the Don has fished really well with some good fish showing. Some of the best days were not ideal conditions either which always makes me laugh. I’ve had a couple of trips to the deveron and it seemed to be much the same. But I haven’t spent enough time on it to be able to say much, unlike the Don
