Modern grassland control wipes out insects

I’VE been living on the same small patch of rural Ireland for more than 25 years and for all that time I’ve been carefully keeping tabs on the wildlife around me.

At this stage, adding a new species to the list of those that inhabit or visit my garden is a rare experience and, for me at least, rather exciting. And it happened the other day.

I was sitting in my conservatory with an early morning cup of coffee when I noticed an insect flitting around in the sunshine on the other side of the glass. I went outside to investigate and it was not, as I first thought, a moth that had been disturbed from its slumbers. It was a small butterfly, about the size of a five-cent coin, maybe fractionally larger.

The under-wing, which is what you mostly see in live butterflies on a sunny day, was a pale bluish white with a few black dots, a bit like the markings on the egg of a song thrush. When I caught a glimpse of the upper wing, it was a brilliant, deep blue with a narrow black border on the edge of the fore-wing.

I went in to get the reference book but I already had a pretty good idea where to look.

What had given the game away was that the insect was flitting around a holly bush. It wasn’t actually a proper wild Irish holly. It was one of those variegated garden varieties. This may be the reason why it didn’t hold the insect’s attention for very long.

The book confirmed my suspicions. I had my first garden record of a Holly Blue butterfly and the specimen was a male.

The food of choice for Holly Blue caterpillars is, as you might expect, holly leaves. Hollies are not common in my part of the world. They prefer a more acid soil. But I’ve planted a few and the book told me the caterpillars will eat other plants.

They have more than one brood a year and in the autumn the caterpillars feed almost exclusively on ivy, which we’ve lots of.

The only other blue butterfly I’ve ever recorded in the garden is the Common Blue. These are nothing like as common as they used to be when I first moved here. The only place I see them regularly now is along the banks of the Grand and Royal Canals. This is because they are essentially a species of unimproved grassland on alkaline soil.

The canal towpaths are precious little strips of this unimproved grassland traversing the countryside and they are made of limestone so, even when they cross an acid bog, they are alkaline.

The caterpillars feed on the leaves and flowers of plants like bird’s foot trefoil, rest harrow, clovers and one or two other related plants. On farms, these plants have fallen victim to modern methods of grassland management so the Common Blue is now no longer common.

I’ve noticed a decline in several other grassland wildflowers in the fields around here. Once, the field outside my study window would have been yellow with cowslips at this time of year. Now you have to go and search for one.

Even the canal banks are not as species-rich as they used to be. Waterways Ireland, their new custodian, has cracked down on illegal grazing and now uses machinery to mow and trim. The more sensitive plant species are disappearing and taking with them some of the dependent insect species. Biodiversity is under threat in the most ordinary of places.