College: CMR National PU College, ITPL, Bengaluru

Sample: Beetle

The site of sample collection: CMR National PU College, ITPL

Date of Collection: 19 February 2019

Date of Observation: 19 February 2019

Students involved: Gopika Anil, Shwetha Santhosh, and Ramya Nambiar

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta

With more than a million species, which greatly vary from each other in taxonomic relatedness, size, and ecology, the beetle is the largest group of insects.

The crustaceans possess hard armor-like exoskeletons that weigh the creatures down. But, instead, the exoskeletons are surprisingly light – even allowing the armor-wearing insects like the beetle, to fly.

Viewing the exoskeleton of the Cotinis mutabilis, a field crop pest beetle, under the foldscope showed it’s composition distinctly. Its exoskeleton is composed of twisted plywood structures, known as Bouligand structures, which help protect against predators. Fibers in this Bouligand structure are bundles of chitin polymer chains wrapped with proteins. These fibers have a diameter of just 20 nanometers.

Exoskeletons of beetles and their associated morphological characteristics can serve many different functions, including thermoregulation. The beetle skeleton acts differentially across the electromagnetic spectrum determining internal body temperatures.


The leg of a beetle was viewed under the foldscope to produce clear and sharp outcomes.

The beetles (like all other insects) have three pairs of legs. The jointed legs are composed of five main segments. The multisegmented legs end in two to five small segments called tarsi. The leg, when viewed under the foldscope appeared in a shade of brown under the light. Tiny hair-like structures could also be seen on the legs. These play a key role in generating thrust during swimming by making the leg more paddle-like.

The shape and size of the leg vary depending on the beetle’s lifestyle. The legs are primarily used for locomotion. It can also be used for swimming, digging and jumping.

beetle’s leg under the Foldscope

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