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More Oxygen in the Air Makes for Bigger Palmetto Bugs

Making It Grow! Minute logo

Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow. Usually after several hard frosts, we get a break from cockroach surprises in the kitchen. So I was surprised when a huge palmetto bug ran across the pantry shelf last week. But it could have been worse.

As plant growth surged during the Carboniferous era, the percentage of oxygen in the atmosphere reached 35% compared with 21% today. Insects rely on passive movement of atmospheric gases through openings in their body to get oxygen for metabolism – with higher amounts of oxygen available, some insects got a lot bigger back then. At the Elmo site in Kansas, a rich deposit for ancient insect fossils, scientists discovered a relative of today’s dragonfly with a wingspan of over two feet! With the decline of atmospheric oxygen levels and the rise of flying dinosaurs and eventually birds, insect size has fortunately decreased – but those roaches are still too big to suit me. 

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Amanda McNulty is a Clemson University Extension Horticulture agent and the host of South Carolina ETV’s Making It Grow! gardening program. She studied horticulture at Clemson University as a non-traditional student. “I’m so fortunate that my early attempts at getting a degree got side tracked as I’m a lot better at getting dirty in the garden than practicing diplomacy!” McNulty also studied at South Carolina State University and earned a graduate degree in teaching there.