The Brimstone has the longest adult life of any Irish (or British) butterfly. The emergence of the adult butterfly begins in late June or more usually in early July and the butterflies may live up to 12 months. It is not active throughout this time, spending much of the time from September to March in an inactive state usually referred to as hibernation. Typically, the butterfly seeks out a safe over-wintering site from mid-September and remains there until around mid-March from when mating and egg-laying occur. By mid-June all or nearly all adult Brimstones are dead and we await the new adults.
However, occasionally, probably as a result of good weather, some survive long enough to see their own descendants fly. In 1934, the great English entomologist and zoological artist, Frederick Frohawk (1861-1946) recorded seeing old, very worn hibernated Brimstones on the wing in the second half of July, in company with numbers of freshly emerged specimens. For the first time in my experience, I observed this generational overlap in Lullybeg in County Kildare. A newly emerged male (male butterflies generally emerge before females) was seen flying energetically along a ride at Lullybeg on June 3rd. On June 7th an old, worn female, which is shown below, was sighted on the same track. She fluttered to feed low down on young bramble before fluttering away to look for buckthorn plants to lay whatever eggs she still holds.
While this overlap in the Brimstone may have occurred before, it is a rare event. There is no reason why a male Brimstone from last year’s hatch would not survive just as long. However, the parents will not mate with their offspring. Brimstone butterflies do not mate in the year they hatch but delay breeding until spring. By that time, only Brimstones that hatched the previous summer will be alive. Nevertheless, living a full year is a great achievement for the adult butterfly and if the climate develops to give us warmer summers Brimstone lifespans may increase.
In late March and early April of this year, Butterfly Conservation Ireland member John Lovatt reporting from Cyprus saw hundreds of Painted Lady butterflies in every direction he looked. He went on to estimate that a million butterflies had arrived in the Gkreko Head district alone. The butterflies that arrived in Cyprus are believed to have come from the Middle East. You can see John’s article in the April archive.
In the past few weeks, a heatwave in Europe means that many Painted Lady caterpillar foodplants may have become desiccated, rendering them unsuitable for breeding. This may be an additional factor driving the Painted Lady to cooler areas to the west and north where foodplants remain nutritious. Massive population accumulations in an area may be an impetus behind population movements; some species form swarms when the population is very large and move together. This creates the dramatic spectacle of clouds of Painted Ladies on the move-I was lucky to see this in south-west Galway in late May 2009.
Since the end of June, large numbers of Painted Lady have been appearing along our coasts and soon penetrated inland. It is notable that the butterflies are faded. It usually takes around two weeks of activity to lose wing scales to the extent being observed now. It is likely that the new arrivals are not recently emerged.
Egg-laying has been reported within sight of the sea at Howth on Ireland’s east coast. Perhaps the female/s that laid eggs there had mated before reaching Ireland and laid soon after reaching the land. In Meath and Kildare, I observed males establishing territories along sunny tracks and at wood edges. Some butterflies are migrating within Ireland, or at least dispersing within a locality; on Tuesday, July 2nd I saw over 20 Painted Lady feeding on bramble at a wood edge. All were unsettled and easily disturbed. On the following day, in excellent weather, I saw just three there.
Whatever their movements within Ireland, it is likely that many butterflies will settle to breed. Indeed, today (July 4th 2019) I watched a female lay two eggs on separate Creeping Thistle plants in my meadow. We will, weather permitting, see the native-born generation take flight from late August. It appears that 2019 will be one of those years when Painted Lady outnumbers the Red Admiral, usually our most numerous migrant.
Keep us in touch with your Painted Lady and other butterfly sightings. Email them to us at email@example.com and let us know the number seen, location name, grid ref and date of sighting. We will post your sighting on our 2019 sightings page.