Wednesday, 10 July 2013

Winter (Dry Season) Ramblings

Remember, click on the photos to enlarge!
 Several trips in recent weeks to a study site south of Cairns, Queensland, near Babinda revealed a small patch of an otherwise extensive area of grassland caused by clearing for various agricultural activities that was attractive to female Painted Grasshawks, Neurothemis stigmatizans stigmatizans. These large dragonflies dart over the fields during the day but as evening approaches, several females alight for the night in a patch of a couple of square metres. We have observed this over a period of a couple of months.
Painted Grasshawk, Neurothemis stigmatizans stigmatizans, female

Why do the Grasshawks choose the same place night after night. And where are the males? (Males have distinctive reddish brown wings) The males may have ended their season and gone to Dragonfly Heaven.

Females may have a good reason to be where they are.
Paddy Bugs or Slender Rice Bugs, Leptocorisa acuta (Thunberg)
There are huge aggregations of Paddy Bugs not far from where the dragonflies spend the night. This bug is notorious for forming aggregations during the dry season and this species of dragonfly is a known predator of this bug.

Paddy Bugs occur in tropical Australia as far south as Brisbane. The species has a broad range in the Pacific and south Asia where it is a pest of Rice. It feeds on rice during the "milk stage" of the development of the rice grains. It causes considerable damage to rice crops. The Paddy Bug also feeds on a wide range of plants ranging from Tea (Camellia sinensis) to Nutmeg (Myristica spp. ). Several biological control agents have been used to reduce bug numbers. These include fungi, egg parasites and encouraging katydids of the genus Conocephalus that feed on the nymphs (see blog below A Night in the Grass). Certain rice cultivars are less attractive to the bugs. These include "bearded" varieties of rice, that is, rice seeds which are covered by sheaths with long hairs that make it more difficult for the bugs to penetrate the husks. 

Thanks to G. Monteith and G. Theisinger for identifications

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