There will be a Music Night of song and dance at Cabragh Wetlands on Tuesday 28th May. Entrance is free and all are welcome. Details of the June 7/8th Bioblitz are going up on our website this week, so please go to www.cabraghwetlands.net for more details. This will be a great family event as well as a chance to improve your expertise in species identification.
The Orange-tip butterfly is out and about at Cabragh Wetlands, celebrating the belated arrival of warmer days, and raising hopes that there may yet be a hot spell of summer in 2013. The Orange-tip is always one of the earliest butterflies to appear, and is perhaps the most instantly recognizable. The male emerges a week before the female; his creamy body and lower portion of his wings resemble many others, but the bright orange patch at the front of his forewings immediately distinguish him from the many whitish butterfly species that will appear over the summer.
As so often in nature, the female is drab by comparison, with no sunburst of colour to mark her out, but simply a rather monochrome creamy-white. While the male’s vivid colour could give it an advantage when it comes to mating, it also acts as a deterrent to would be predators – in effect displaying a message to passing birds that they are not good to eat, tasting strongly of garlic and mustard oils accumulated when they were feeding in their larval stage. Birds will be unwilling to sample a second Orange-tip, so the male gains from displaying his presence so prominently. Females, busy laying eggs in the right place, have less need for camouflage as they are far more static, rarely taking to the air. Developing an orange wing tip has proved to be unnecessary evolutionary adaptation.
As spectacular as its orange splash may be, the true beauty of the Orange-tip lies in the delicate green frond pattern on the underside of its wings. This pattern looks very like a small patch of lichen, and gives the resting insect a wonderful camouflage if it sitting on a tree or flower. The delicate shades of yellow and grey combine with the green to create an extraordinary mossy web. Some say the green that some of us see is illusory, forged from the combination of cream, yellow and brown.
At Cabragh the Orange-tip is usually to be found near patches of Cuckoo-flower, or Lady’s Smock, which is its principal larval plant. Females also rest on garlic mustard and cow parsley, which give them great camouflage. If you look under the flowers of the host plant in June, you may see the tiny eggs, which are laid singly and change colour over a few days from pale pink to orange. By laying perhaps as few as one egg on each plant, the butterfly maximizes the chance of a good number of the eggs hatching and reaching maturity. If all eggs were laid on one plant, the whole brood could so easily be destroyed by a passing pony, an over-zealous strimmer, or even you or me out picking flowers for the kitchen table.
After a week or two the egg will hatch, and the tiny caterpillar burrows into the flower to eat the seedpod (and only the seedpod) of its host plant, starting at the end of the pod and munching its way back to the middle. The caterpillars are pale green, solitary and cannibalistic – quite happy to eat another Orange-tip caterpillar that has the temerity to try and share the same plant. A tenth of caterpillars end their days as food for their own species, and 15% die of starvation as they grow (so try to ensure there are plenty of the best host plants in your area). Others succumb to predators, so that barely a quarter reach caterpillar maturity and become a chrysalis, in which form it hibernates for the winter – so the new butterflies we see in 2013 are last year’s caterpillars.