They've Started!

At exactly 6.38 pm, AEST on 14 September the first Green Grocers of the season, Cyclochila virens, were heard on Butler Drive,  Kuranda. There was not the loud chorus that one might expect. Perhaps, the dry conditions or the fact that not many had emerged is the reason for the supposed diminished numbers.

Over the next few months the cicadas will sing around this time, but each day the chorus begins a few seconds later than the previous day. Towards the end of their season, the chorus will commence well after 7.00 pm. Some interesting biology is to be learned here. Surely the individuals at the end of the season are not the same as those that have just started. So population has some rather peculiar triggers relative to the activity of the adults cicadas, perhaps photoperiod but how is this transmitted to nymphal cicadas in the ground? Many local birds and reptiles depend on the large cicadas for food so their activity is an important part of the food chain here.

Spring Is Here

On 10 September 2017 we heard the first Northern Green Grocers, Cyclochila virens Distant, Cicadidae, of the year in our piece of rainforest.

Singing commenced at 6.35 pm (Eastern Standard Time), shortly after dark and continued for less than 15 minutes. The nightly serenade will continue for several months and start a few seconds later each night until by summer the singing begins around 7.15 pm. The intriguing bit is that it could not possibly be the same adults singing for months and months but newly emerged individuals replacing the oldies. So what is the explanation for the later and later starts and how is this information is received. Could temperature and/or day length be responsible for this behaviour. I'm sure someone has studied this for this large, iconic Queensland insect.

Reference
Moulds, M., 1990. Australian Cicadas. 217 Pp. New South Wales University Press, Kensington, NSW.