Donal Hickey: Why so few butterflies this year?
Mark Wire Conservation/pa Picture: Butterfly Red Admiral Searle/butterfly
Many people have been noticing a scarcity of butterflies this summer. It doesn’t seem summer without them, but then again there is also a definite shortage of the heat we hope for at this time!
Some readers blame the unseasonably cooler weather for keeping butterflies away. And that, indeed, may be at least part of the reason.
This year I’ve seen only one butterfly in the back garden where buddleia plants have been like magnets for them every summer. Bees are also not as numerous, but at least they can be seen.
A report, in June, from the Burren, County Clare, said there were masses of flowers, but a shortage of butterflies. The situation seems similar in England, as information received by Butterfly Conservation Ireland (BCI) indicates.
A monitoring scheme by our National Biodiversity Data Centre found an overall 35% decline in the butterfly population between 2008 and 2021, with no positive trends for any species. One of the main causes is loss of habitat, as is the case with other wildlife.
The Meteorological Service said May was the warmest May on record. June, however, was described as cool and dry with temperatures below average nearly everywhere. All available sunshine totals were below their long-term average.
It remained cool in the first half of July, with day-time temperatures ranging from 12° to 18° Celsius. Farmers tell us growth is well back.
Interestingly, the BCI says below-par weather is unlikely to be the sole reason for butterflies not showing up. It also points out, however, that butterflies are strongly influenced by weather conditions: their emergence is greatly delayed by prolonged, cool temperatures.
But, there appears to be a particular issue with species such as small tortoiseshell, comma, peacock, and red admiral. There are very few records of these butterflies this summer.
Insects such as wasps, which feed on the larvae of other insects, affect all four. There may be an increase in the population of these preying insects, the BCI muses.
Cool conditions, nevertheless, cannot delay the emergence of these butterflies indefinitely, BCI adds. When they emerge, we might understand the nature of any impacts on their populations.
It ends on a positive note: “Most of our butterflies are adapted to cool weather, but the adults thrive in warmer weather allowing them to feed, disperse, find mates and lay their eggs. Prolonged bad weather damages populations which rebound quickly in years with better weather. Provided we are looking after their homes."
Hopefully, we may yet get fleeting glimpses of butterflies, perhaps only for a few moments. Most adults live for only around two weeks.