Top 10 Oldest Creepy-Crawlies

These bloodsuckers have been annoying everyone since the earliest days of human civilization. Following in the footsteps of its main food source, researchers believe the human head lice evolved from its chimpanzee predecessor and dates back to over 5.5 million years ago. While that does not seem too old in the grand scheme, entomologists have discovered fossil lice that suggest the parasite existed during the age of dinosaurs, which is at the very least 65 million years ago. Currently, the earliest identifiable sample sits at around 44 million years old and holds many similarities to the modern parasite that infests aquatic birds.

While the belief that cockroaches could survive a nuclear explosion is mostly a myth, these crawling insects have a long and storied history. As part of the Blattodea order, the earliest roach-like insects date back to 320 million years ago, but these species share too little in common with the modern cockroach to be considered as direct ancestors. However, cockroaches definitely co-existed with dinosaurs during the early Cretaceous period and researchers believe that termites also evolved from the same family. In 2015, a 100 million-year-old new species of cockroach was discovered, and it is absolutely terrifying!

Widely regarded as the most diverse group of insects, the story of the beetles starts with the extinct Protocoleptera, which served as precursors to the modern bug and can be traced back to 280 million years ago. The modern beetle took a while longer to properly form, but all four currently active suborders were present during the late Triassic period, so – at the bare minimum – the insect's evolutionary lineage goes back 200 million years. Unlike other groups, a beetle's membrane is protected by a hardened forewing known as the elytra, which protects the insect from parasites and predators.

Belonging to the Diptera order, flies have a complex history, with entomologists predicting there are over a million different species. Dipterans existed during the Middle Triassic period, which is over 200 million years ago; however, flowering plants were not available at the time, so the ancestor of modern flies probably came into fruition during the Cretaceous period. Due to changes in the eco-space, Dipeterans underwent three main diversification periods that gave rise new species; the first happened 220 million years ago, the second around 40 million years later, and the last dated back to 66 million years ago.

We opted to pack these three creepy-crawlies together as they all belong to the same Orthoptera order. A 2015 study by Hojun Song detailed the evolution of these three insects, explaining that Orthopterans originated over 300 million years ago before dividing into two suborders that gave rise to a variety of superfamilies. With over 4800 species, crickets debuted around 250 million years ago and are the oldest of the bunch, while katydids and grasshoppers date back to approximately 100 and 65 million years respectively. Despite being the trio's youngest, grasshoppers are actually the most diverse group out of the three, with around 8000 species.

Believed to be among the first creatures to experience flight, these insects originated as wingless creatures more than 450 million years ago, but the first flying organism came around approximately 50 million years later. Belonging to the Odonata order, Dragonflies and Damselflies are predators who feast upon other insects and can be found all over the world. Neither insect has changed much over the years, which is quite impressive since their earliest known origins go back to the Jurassic period. In other words, dinosaurs might have ruled the world, but they could have used some bug spray.

Regularly found living underneath rocks; these tiny, wingless monstrosities are the oldest insects on the planet. A 2014 study brought together over a 100 scientists to map the evolution of insects by using DNA data and revolutionary analysis techniques, with a focus on the relationship between different species. Among many other findings, the results asserted that land-based insects emerged approximately 500 million years ago and – in all likelihood – the earliest creatures resembled the silverfish. Considered one of the most primitive insects on Earth, silverfish have never grown wings, possess long antennae, and resemble a fish.

Defined by their flat bodies and dozens of legs, these arthropods are regularly cited as the first creatures to permanently transition from the sea to land. In 2004, a 420 million year old millipede fossil was discovered that contained holes to absorb oxygen, confirming that the arthropods had colonized by the Silurian period. Labeled as living fossils, physically, millipedes have largely stuck to their original shape; however, due to an overabundance of oxygen, the arthropod's ancestors grew to massive sizes that could exceed one meter.

Classified as arthropods rather than insects, primarily due to their unsegmented body and eight legs, mites are everywhere but slip by unnoticed due to their small size. A member of the Acari group – which also includes ticks – these arachnids are extraordinary entities that can be found in nearly any aquatic or terrestrial habitat, and the majority are predatory by nature. In comparison to some other entries, most of the fossils are relatively recent; but in 2002, a 480 million-year-old mite was discovered in Sweden.

Yes, these eight-legged nightmares pretty much inherited the Earth. Evolving from a crab-like ancestor, true spiders are confirmed to be over 300 million years old, although older fossils have been discovered that share traits with the arachnid but are classified under different orders. The modern spider is defined by a silk-spinning organ known as the spinneret, which appeared around 250 million years ago. Fun fact; currently, there are over 45,000 named species of spiders in existence, but researchers believe the true number of total species is more than double that. Maybe fun is not the right word.