Buggin with Bridgey – November 2023
Buggin with Bridgey is a Monthly report of sightings from the Let’s Go Buggin Cairns Nature & Photography Tour in the Cairns Botanical Gardens. As the months roll by, subtle changes in the seasons bring sightings of new creatures and this report aims to give people a wrap up of the current animals seen as well as provide an ongoing citizen science account of our wonderful critters that can be seen in the Wet Tropics of Queensland.
Green Tree Ants and their Relationships
Green Tree Ant Workers with Larvae building a nest
The wonderful world of Green Tree Ants and their Relationships! These remarkable creatures are not just your ordinary ants. Oh no, they’re nature’s miniature architects, social superheroes, and botanical bodyguards all rolled into one. These highly defensive ants are one of the common creatures found in the Wet Tropics of Queensland.
Green Tree Ants (Oecophylla smaragdina), also known as Weaver Ants, live in a society that is highly organized and hierarchical. The colony is composed of multiple nests, and each nest has a distinct role and function in the colony. They have strong relationships with many other lifeforms that share their environment.
Let’s start with the relationships within the colony. In each nest, there is a queen that lays eggs, and worker ants that carry out various tasks such as foraging for food, nest building, and caring for the young. The queen is the highest-ranking member and is responsible for reproducing and ensuring the continuity of the colony. The nests of the colony are built by the workers with the larvae. While some of the workers use their combined strength as an army to hold and bring leaves together, another group of workers carry larvae to the site and quite literally use the larvae like a glue-gun. The larvae produce the sticky silk that when hardens, sticks the leaves together. This is a blatent example of child slave labour. The above picture shows both the workers and larvae carrying out this imperative task.
Green Tree Ant Queen after exiting her colony. Green Tree Ant Queen with her first clutch of larvae.
But the Green Tree Ants relationships don’t end there. These tiny marvels of nature have a deep connection not only with the towering trees above but also with a host of other inhabitants in their ecosystem. Relationships of a Mimicry, Farming, Symbiosis and of course Predation are all part of the way of life for this species.
The football-sized nests in trees provide the homes and protection for the colony and most importantly the queen and her growing brood of larvae. In return the tree gets a built-in defence of would-be leaf eaters. This symbiotic relationship has been recognised by the scientific community and is even used as bio-warfare in China and S.E. Asia. Reports of trees with Green Tree Ants produce more fruit, have more foliage and reduces the need for pesticides. So, before you reach for the bush-trimmers perhaps you should be content to do the ’Green Ant Dance’ once in a while. A garden with green ants is a healthy one!
Predator – Swifts’ Ant-hunter Spider (Zenodorus swiftorum)
Our most common Jumping Spider in the Wet Tropics by a long way, and it makes sense that a predator of an extremely common species would have another common species that preys on them. I regularly see these Saltids with their chosen meal of Green Tree Ants. It’s a great time to photograph them as well as they are focusing on the ant rather than skipping about which is their normal behavior. It’s my belief that they are extremely zippy and fast due to their chosen meal could fight back and the tables could easily turn if a foot is put wrong.
Swifts’ Ant-hunter Spider (Zenodorus swiftorum)
Aggressive Mimicry – Green Ant-Hunter (Cosmophasis bitaeniata)
Green Ant Hunters are my favourite Jumping Spider (Salticidae). Not only is she the most beautiful but she’s super clever. Not only physically taking on similar colouration, but their real mastery comes from their ability to copy the pheromone of the ants and live nearby a nest without being detected. This behaviour is referred to as ‘crypsis’, and is classified as Aggressive Mimicry. They are able to enter the nest completely undetected stealing the larvae in plain sight! It really is some incredible predator evolvement.
Green Ant Hunter (Cosmophasis bitaeniata)
Aggressive Mimicry – Green Tree Ant-mimic Spider (Amyciaea albomaculata)
Featured mid-capture, this Crab Spider uses Aggressive Mimicry to prey on its chosen victim of Green Tree Ants (Oecophylla smaragdina). Quite a challenge to photograph due to their skitzy behavior, however, I was fortunate to come across a scene in which the spider had just captured an ant and was in the process of hauling it upwards via its abseiling silk line from an above branch.
Green Tree Ant-mimic Spider (Amyciaea albomaculata)
Batesian Mimicry – Brown Bean Bug (Riptortus serripes)
Being a vulnerable species without any real defence has inspired some Batesian Mimicry within the insect world. One example is the developing young of these Brown Bean Bugs. In their early life stages (instars) they appear as a Green Tree Ant to help it evade some would-be predators.
Brown Bean Bug (Riptortus serripes)
Farming
Green Tree Ants are great multi-taskers. They are known to ‘farm’ certain species in order to collect Honeydew. A sweet substance that many species of aphids, scale and leafhoppers secrete. The ants tickle the animals to encourage this secretion and then they are rewarded with a sweet snack. There are also a few species of Blue Butterfly that larvae (Caterpillars) are protected and are attended to by Green Tree Ants. The caterpillars success rate into adulthood is greatly increased if they have the protection of the ants.
Green Tree Ants farming and attending to Aphids. Green Tree Ants attending to Arhopala Butterfly larvae.
I hope you enjoyed seeing some of the examples of the relationships of Green Tree Ants in the Cairns Botanical Gardens and the Wet Tropics of Queensland. If you would like to take a deeper dive into some other encounters you can check out my Let’s Go Buggin Project on iNaturalist here.
Keen for a Let’s Go Buggin Tour? Use ‘BRIDGEYBLOG’ as the coupon code for 15% discount on your tour booking here.
Next Blog in late October.
🐜 💚 📸
Bridgette
