Sweet Potato Weevil from Hawaii

A Sweet Potato Weevil?
Sat, Dec 6, 2008 at 7:15 PM
Hello Bugman!
About a week ago I threw an old sweet potato into the yard. Today I went to move the sweet potato to a garden area just in case it was going to grow and I found some odd little red and black insects collected underneath it.
The bugs were a little less than a centimeter long and they had black heads and abdomens with thoraxes that looked as if it was made of two red spheres. Their heads had a long black snout with antennae at the end of the snout. When anything touched them they dropped to their sides as if they were dead and a minute later they would revive themselves and move around again. They also pulled in their antennae when they played dead. I browsed through insect images online and I think they might be sweet potato weevils but I’m not entirely sure. That bug in the photo was the only one that remained on the sweet potato when I moved it, the rest fell off playing dead.
Thank you for your time reading this! And pest or not, they all were left unharmed after the potato was moved.
Hilo, Hawaii

Sweet Potato Weevil
Sweet Potato Weevil

Hi Yvonne,
You are absolutely correct. This is a Sweet Potato Weevil, Cylas formicarius. It is a perfect match to images posted to BugGuide which states: “Range Worldwide (mostly tropical and subtropical). Introduced in North America, where found from South Carolina to Florida, west to Texas” and “Larvae bore in sweet potatoes. Tiny white eggs are laid in punctures made in vines near ground, or even in stored potatoes. Larvae burrow in and feed for 2-3 weeks, then pupate in a burrow (2). Also attacks morning-glories and some Asteraceae.”

Sweet Potato Weevil
Sweet Potato Weevil

Thank you so much for the identification! I am one insect identification smarter now 🙂  My neighbors recently dug up all of their sweet potato plants so perhaps they wandered from there to my yard looking for food. I didn’t know these weevils existed until I saw them under the sweet potato, it’s amazing how insects have their own little niches in unexpected places. Thank you again for the identification!

1 thought on “Sweet Potato Weevil from Hawaii”

  1. Dear Yvonne,

    I am writing a field guide,”Beetles of Eastern North America” for Princeton University Press that will cover 1,400 species in color. This book is part of the same series that includes Dave Wagner’s caterpillar books and Dennis Paulson’s recent odonate tomes. I would like to use one of your images of Cylas formicarius that appear on What’s That Bug? that you posted back in 2008.

    Unfortunately, there is no photo budget for the field guide, but I can promise you a copy of the book when it is published within the next two years and my eternal gratitude! Might you be willing to contribute this image to the book?

    I look forward to hearing from you.

    Sincerely, ART EVANS
    [email protected]


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