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Entomology is the branch of science comprising the study of insects. These usually small, sometimes weird-looking but fantastic animals belong to the largest phylum in the animal kingdom, the Arthropoda; other members of this group include crabs, lobsters, spiders, centipedes and millipedes. Till now, they are known more than one million species, even though it is estimated that that number might be around 5 million. Insects are represented by a huge diversity in terms of shape and color, but also habitat form, food source and locomotion.
They are crucial to every and all ecosystems since they take part in key processes such as pollination (contributing to the reproduction of plants and the formation of fruits), decomposition of organic matter (leading to the recycling of soils’ material) and serving themselves as prey to other animals.
Music of the crickets!
Firstly, I decided to address the crickets. If you ever passed near a field area during a summer’s dusk or night, you might have heard one of the singings of nature. The male crickets are the only ones that produce sound to attract females doing copulatory courtship, vibrating specific parts of their wings to produce it – the scraper, on the upper surface of the lower wing, and the file, located on the underside of the upper wing. This phenomenon is called stridulation. The sound is received by specialized organs located on the front legs: the oval eardrums or tympana.
The process of stridulation is also reported on other members of Orthoptera, such as katydids and grasshoppers. Even on members of the order Hemiptera, such as the cicadas. However, the last two mentioned have different methods to achieve the production of sound.
The appetite of the monarch caterpillar!
The monarch butterfly (species Danaus plexippus) is an iconic species of butterfly known for its bright-orange pattern with black veins in adults and its incredible migratory journey across North America.
After the adult butterflies lay a single egg on a milkweed plant, it takes around two weeks for the baby monarch caterpillars to hatch, eating their way out of the eggshell and then going for the eggshell itself. If lucky, for the neighbour’s as well!
To get to a considerable size to construct the chrysalis form, the caterpillars voraciously feed on milkweed leaves for the following three weeks. Although this plant is venomous for the most, the monarch caterpillars developed immunity to its toxins and use them to their benefit, during both larval and adult stages, so that the predator avoids predating these individuals. Beyond that, feeding on milkweed presents them with little or no competition for food.
Fire ants’ architecture!
Beyond being fast and effective colonizers, fire ants are also known to bio-build architectonic structures with their bodies. If dropped on a body of water or near a standing high object, the ants reorganize between them to construct fantastic structures, from floating disks to ant towers (which can reach 30 ants tall!). When it comes to achieve this, the ants rely on their senses of touch and smell, so they can distinguish what is near them.
To build the floating rafts, the ants link their mandibles and legs together, forming a buoyant living net. Their setae (ants’ body hairs) trap hair bubbles that prevent the individuals on the base of the raft from staying completely submerged, enabling it to float. The dry and safe core, the best spot on the raft, is reserved for the queen and her larvae. The colony can drift this way for weeks, even though it comes with the cost of losing some lives to predation and others.
Dragonflies on the hunt!
Dragonflies are incredible animals and some of the most successful predators in the animal kingdom. While the dreaded white shark’s catches are only successful half of the tries, the dragonfly has a 95% chance of having a good outcome of the chase. The dragonflies predict their prey´s movement, instead of reacting to it and going for the attack, as it used to be thought.
This effective hunter approaches its prey from below, as it manoeuvres its body to orientate it towards the capture site, and the head remains fixed onto its target, following its motion with almost-perfection. The fore and hind wings have independent motion of each other, giving the dragonfly a lot of freedom to move. It can also hover and fly backwards.
Carolina Simões
References
Brower L. P., Glazier S. C. (1975). Localization of Heart Poisons in the Monarch Butterfly. Science, 188(4183): 19-25
Holland, Mary (2021, July 26th). “Cannibalistic Monarch Larvae”. Northern Woodlands. Available at: https://northernwoodlands.org/knots_and_bolts/monarch-larvae
Howard, Brian Clark (2015, October 5th). “How Ants Survive Flooding by Forming Giant Rafts”, Weird and Wild. National Geographic. Available at https://www.nationalgeographic.com/animals/topic/weird-wild
Foster P. C., Mlot N. J., Lin A., Hu D. L. (2014). Fire ants actively control spacing and orientation within self-assemblages. The Journal of Experimental Biology, 217: 2089-2100
Combes S. A. (2015, January 15th). Dragonflies predict and plan their hunts. Nature (News & Views), 517: 279-280. Available at: https://www.nature.com/articles/nature14078
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