Question of the Week Number 1: May 31, 2018
“Neil, what is eating these circular holes in the flowers of my bougainvillea? What can I use to stop it?”
This is the work of the leaf-cutter bee. The adult female bee visits roses, bougainvilleas and other plants that are attractive to her, cutting nearly perfect circles out of the edges of the floral bracts and leaves. Sometimes you will see remnants of the leaf tissue where she hasn’t completed the job and where the area within the circle has dried and browned.
Once she has a piece of plant tissue cut loose, the bee flies away, carrying it to a faucet or downspout and builds her nest from the parts. I’ve had the experience of turning on a faucet to fill a bucket of water only to have a wad of this dried debris blow into the bucket on the first wave of water.
There isn’t much way to spray for this insect. She isn’t present more than a few minutes, so you’d have to have perfect timing to be able to catch her. And she doesn’t consume any of the plant tissue, so stomach poisons won’t bother her.
The good news, however, is that this damage is essentially cosmetic. The plant keeps on growing as if nothing had happened. The whole affair runs its course fairly quickly and life can return to normal.