Too Cold or Too Wet for Butterflies?

 

Photo 1: Orange-Tip (female) in the Secret Garden (2nd May 2024)

We have seen the odd butterfly in the garden - holly blue, small white, red admiral, peacock - but sightings have been few and far between. This female orange-tip butterfly appeared on a rather cold dank day at the beginning of May. A recently emerged specimen, it remained on the poppy flower bud for at least 15 minutes trying to dry out ready for flight.

Photo 2: Orange-Tip (side-view) in the Secret Garden (2/5/24)

Just a few feet away, one of the orange-tip's food plants - cuckoo flower (Photo 3) - is growing. Coincidence or not?!

Photo 3: Cuckoo Flower in the Secret Garden (6/3/24)

We have seen orange-tip butterflies away from the garden - notably in Lea & Paget's Wood.

Holly Blue butterflies were first spotted in the garden in late March but didn't hang around long enough for the photo shoot. On the 11th April, I managed to photograph and video this recently emerged example.

Photo 4: Holly Blue Butterfly on the Potato Patch (11/4/24)

Video 1: Holly Blue Butterfly Takes Its First Steps

Video 2: Holly Blue drying out its wings in the cold April wind

Why are the garden butterflies so late this year? Higher spring temperatures encourage earlier emergence. This spring (March & April) has, on average, been on the warm side - about 2 ℃ above the 1961-1990 CET mean - though mean daily temperatures have oscillated between hot and cold spells. Figure 1 compares the average monthly temperatures in Hereford for March and April, covering the years 2020 to 2024. So nothing is obviously untoward about 2024 - not the warmest (2020) or the coldest (2021).

Figure 1: March and April Monthly Mean Temperatures (2020 - 2024)

Another weather factor that could impact the number of butterflies is rain. Once the butterfly emerges from the chrysalis, it needs to let its wings dry out so it can fly. It needs to fly to feed and find a mate. And, of course, it cannot fly in heavy rain or strong winds for that matter. Figure 2 shows the March and April rainfall values in Hereford for the past five years, along with the sum of both months.  

Figure 2: Hereford Rainfall in March, April and Combined Months (2020 - 2024)

This year, 2024, has been the wettest by some margin of the last five years. This may have had a dampening effect (pun intended) on the butterfly population.

There are other factors to consider such as wind speeds, frequency and duration of storms, availability of food plants, cold/wet winter conditions affecting butterflies that overwintered as adults, and whether the previous breeding season was successful.

For the moment, let's just be thankful we can still enjoy these magnificent creatures and help their conservation by gardening naturally with nectar-rich plants.