Agave Weevils: a Water-wise Gardener’s Nightmare
I started noticing that one of my oldest agave plants had started sending me a message in what looked like an ancient alien language (note: I have been playing a lot of Legend of Zelda: Tears of the Kingdom, so that may be why my mind jumped there). I was blissfully unaware of the horror that is the Agave Snout Weevil.
I started paying more attention to the plant, noting it had pups. I wondered if it just needed extra water (despite never needing much water before) and was stressed. But the illness progressed and I eventually saw the whole plant leaning over, a huge hole where it’s core had been, and the poor doomed pups just trying hold on and survive.
A plant autopsy and a little research later and I knew the culprit: the Snout Weevil. The beetle has a sharp snout that penetrates the agave’s tough skin, infecting the plant with a bacteria that softens the core. Then it lays its eggs. The pupae that hatch then eat the softened core of the plant, become beetles themselves, and then walk off (they do not fly) to find more host plants to murder.
These weevils are a real problem in Mexico and Southern California, so I was surprised to have them show up in a well-established succulent garden. I have not brought new plants to that part of my yard in a long time, so I know I did not bring home a nursery stow-away. That means the little jerk who took out my pointy plant friend just sauntered up to it from someone else’s garden.
The protocol for dealing with these tiny monsters is to remove the plant and dispose of it completely (no home composting!). Then, dig up the soil surrounding it and search for more grubs and beetles, killing them all with extreme prejudice. Lastly, watch any other plants nearby carefully for signs of infestation.
There are preventative measures, but most are chemical pesticides that I choose to not use in my garden (at least for now. My tune may change if more plants succumb). Some are sprays, some are granules. All are nasty broad-spectrum pesticides.
The one organic method (other than “stop growing agaves at all”) is to use a mulch of worm castings. They supposedly make the ground around your plants harder for the beetles to travel across, as they damage the beetles’ chitinous shells. I really hope that is correct, because that is what I plan to use.
I hope you never find yourself with an agave weevil infestation. If you do find your beautiful agaves showing signs of infestation, take care to remove the plant as soon as you can and warn your neighbors.
Additional resources:
Backyard Gardener: Agave Snout Weevils
Debra Lee Baldwin: Agave Snout Weevil Prevention and Treatment