Sunday, June 5, 2011

The spotted cucumber beetle

The spotted cucumber beetle, Diabrotica undecimpunctata.
Cucumber beetles are pretty insects with bright yellow-green bodies and contrasting black spots, head, legs, and antennae. They are about 1/4 inch long.

They are sometimes mistaken for rare green ladybugs. Nope. They are beetles, like ladybugs, but in another scientific family -- the Chrysomelidae -- commonly called Leaf Beetles.

 The cucumber beetle's good looks don't count for much with gardeners and farmers; the little green varmint is a big agricultural pest. Cucumber beetles eat more than cucumbers. Their menu includes melons, squash, pumpkins, corn, beans, soybeans, and even cotton.

Adult cucumber beetles munch on leaves, fruits, stems, and other juicy plant parts and the little yellow larvae burrow into plants mouth first, eating as they go. Like a superhero with an alter ego, the larval stage of the cucumber beetle is also known as the notorious Southern Corn Rootworm! Cucumber beetles are found throughout North America even where there are no crops. I find them in Brooklyn on the leaves of ornamental plants and in rose blossoms.

Every year some of them overwinter as adults under leaves or trash.  They emerge in spring and lay eggs. After a few weeks, the larvae become handsome adults. There is time for multiple generations each summer.

Their lives are so short that I am inclined to forgive them for eating cucumbers. But I am not a gardener or a farmer, just an insect watcher who sometimes wonders what it would be like to be a green beetle. Dylan Thomas wrote a  poem that begins -- To-day, this insect and the world I breathe. Today, me too.


  1. Informative and poetic. I have them in my garden, but so few that I leave them for the birds.

  2. They are so pretty that I always feel a little happy when I see one. -- Julie

  3. Woke up this morning to find one munching on the leaf of a young Mexican Sunflower plant we're preparing to plant outside for the summer. It didn't take it long to consume so much of the leaf. Very active beetle in Herndon, VA.

  4. Oh no! Sorry about your sunflower. Hope it pulls through. Julie