Fossil Friday: Insects Part 2

| Patricia Bujard

Some people know enough about prehistoric life to know that flowers and grass did not appear until the Cretaceous period, near the end of the dinosaur’s reign here on Earth. So surely butterflies, bees, and all those kinds of insects didn’t show up at least until about the same time as flowers right? Wrong!

When tracing back through the many insect groups (boy did I open up a can of worms there!) I was surprised to discover that there were members of the butterfly and wasp groups already around during the Jurassic period, long before any flowers grew.

Technically the groups are called Lepidoptera (butterflies and moths) and Hymenoptera (wasps, bees, and ants), and the critters flying around weren’t exactly like the butterflies we see fluttering from flower to flower or the wasps buzzing around an angry nest in the tree, but…they’re still relatives, and what on earth are they doing when there are no flowers around?

Before colorful butterflies graced the Earth with their beauty, there was the Caddisfly. These insects are close relatives of modern moths and butterflies, and fossils have been found from the Early Triassic period. They have larvae or “caterpillars” that spin silk cocoons, often strengthened with things like pebbles, leaves, twigs, sand, or any sort of debris. These larvae are aquatic, and eat anything from algae, other insects, or even tiny particles in the water, depending on species. The adult Caddisflies do not eat anything at all, and live very short lives.
Sawflies appeared in the Triassic period, and are distinguishable from modern wasps because they don’t have the thin “wasp waist”. They get their common name from the females’ ability to saw into plants with her ovipositor, a stinger-like structure used for laying eggs. The larvae are voracious plant eaters, like caterpillers, but stay together in groups, and can stay in this stage for months, or sometimes years. Once grown, the adults live on sap or honeydew (nectar-like bubbles aphids produce) for about a week.
The Horntail, or Wood Wasp, is within the sawfly family. What looks like a stinger is just a hardened horn-like structure, and not used for defense. The females find the perfect tree and drill deep into the wood with their highly specialized ovipositor, which deposits the eggs into the hole once she finds the ideal spot. The larvae can wait for several years before finally settling down just under the bark to prepare for their pupa stage. The adults then climb out of their old skin and chew their way out of the bark, no matter how hard. Some modern Horntails have chewed their way through a sheet of lead!

Resources:

Any sort of list for prehistoric insects was mostly unhelpful. Research for this series mostly involved painstaking unwinding of threads from modern groups, then tracing back on which ones are the oldest and most “primitive” groups. Luckily, Wikipedia has a handy little chart on the upper right-hand corner for almost every insect genus and family that says when in time it appeared. I would then trace those lineages and see if I could find fossil versions, or modern species that look nearly identical to their fossil ancestors.

Once I crawled into the rabbit hole I just had to keep going, even when I realized I’d bitten into quite a bit more than I could chew! I hope you enjoyed it as much as I did! 😀

I am eternally grateful that Wikipedia is such a great resource. From the sheer number of insects I discovered I’m afraid I did not have the time to cross reference with other resources, but you can always look into the many resources Wikipedia lists at the bottom of each article if you want to find out more!

“Dicondylia.” Wikipedia, https://en.wikipedia.org/wiki/Dicondylia#Taxonomy

“Lepidoptera.” Wikipedia, https://en.wikipedia.org/wiki/Lepidoptera

“Caddisfly.” Wikipedia, https://en.wikipedia.org/wiki/Caddisfly

“Hymenoptera.” Wikipedia, https://en.wikipedia.org/wiki/Hymenoptera

“Sawfly.” Wikipedia, https://en.wikipedia.org/wiki/Sawfly

“Wasp.” Wikipedia, https://en.wikipedia.org/wiki/Wasp

“Horntail.” Wikipedia, https://en.wikipedia.org/wiki/Horntail

3 thoughts on “Fossil Friday: Insects Part 2”

  1. Very interesting! I will be the first to “bug” you with my questions and comments. How old are the dragonflies? Were the dinosaurs bothered much by insects such as stinging and biting insects?

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    1. Dragonflies (family Odonata) have been around since at least the Carboniferous Period, approximately 325 million years ago. We know that mosquitoes and ticks were around in dinosaur times, but both of them appeared rather late in the Mesozoic Era. Mosquitoes are actually a highly-evolved form of fly. The oldest flies date to the late Triassic Period about 220 MYA, and the oldest mosquito that we know of dates to the late Cretaceous Period about 80 MYA. Ticks first appeared during the Cretaceous Period. One specimen of feathers preserved in amber, which was found in Myanmar/Burma and dated to 99 MYA, had ticks on it.

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    2. Thank you! I’m glad you like it, I’m having a lot of fun with all these bugs 😀

      Jason is right, the dragonfly family has been around for a very, very long time, though their relatives in the Carboniferous period weren’t exactly like they are today. Mosquitoes, fleas, and ticks didn’t appear until the Cretaceous, but there are many “true flies” that bite (though they may not suck blood, more like modern horse flies than mosquitoes). Females are almost always the only ones that bite, because they need the extra protein and iron to lay eggs, something they can’t get from tree sap, nectar, or honeydew. For the same reason, predatory flies almost never bite other animals except occasionally for defense. I’ll be covering flies and their relatives int his week’s Fossil Friday. 😀

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