Black weevil found in Agave

[MattyB]

Hey y'all,

I just found an Agave americana that had completely collapsed and when I turned it over it had larvae grubs all partying up inside of it. I thought, "oh crap, palm weevil!". But after some googling I'm pretty sure it's the Agave snout weevil. It's only like 1.5 cm, and has a very curved snout. I've kept specimens of both the adult weevil and the larvae and I called the pest hotline just in case so they can look at the pics I took. I'll upload them for you guys on Monday when I get back into the office.

Has anyone had problems with this Agave snout weevil (Scyphophorus acupuntatus)?

I've had some holes in the crownshaft of my largest Roystonea and I'm wondering if this weevil will attack palms as well.

[John in Andalucia]

I've not seen this weevil around in Spain. We have a couple of 6-foot Agave americana in our cortijo garden. Maybe you're familiar with this map of recorded incidences for Scyphophorus acupunctatus:

http://www.discoverl...us+acupunctatus

[MattyB]

Thanks john that was informative

[palmaddict]

Matt,

I have given up on growing some agave types due to the weevil. Highly resistant to treatment. Overwatering makes infection more likely. Agaves that are more tropical seem to do better. Plants collapse in a matter of days. I have gotten more.into aloes as they one do not flower and die, they tolerate more water than agaves and many can handle clay, and they do not suffer the weevil problem. I know a succulent grower who has multiple growing grounds. He has given up growing agaves at some grounds due the weevil. Not all aloes are like dichotoma which if you look at it the wrong way it rots out. Aloe hurcules which is now in tissue culture makes a beautiful tree aloe. I have about fifteen of them and as they are a hybrid with bainsii they can take water. I only put agaves where drainage is superb. I need to get around to posting some pictures. Agaves that pup and some don't I do not worry about as the pups replace those the weevils get to. I have seen two of the same agave clone one the weevils devour and the plant two feet away is untouched. It cannot be genetics since the one plant is a pup of the adjacent.

Patrick

[MattyB]

Interesting. this agave was planted on rock with little to no soil and never watered in 4 years. The slope is south facing and literally bone dry

[GeneAZ]

This weevil is the bane of all of us in Arizona. I understand that, technically, the grub is not killing the Agave, but the ensuing bacteria and rot from the chewing that ultimately causes the collapse. The suckers that can arise after a plant dies this way are rarely infested and can be removed and grown on to continue the clone.

Bayer makes an effective systemic granule for this pest, but it must be re-applied every few months. Diazinon as a spray and drench is also effective if applied at 4-month inervals throughout the growng season. I wish both companies would make a time-released spike that lasts 8 or 9 months.

We have a HUGE beetle here the size of a small sparrow which targets the Palo Verde tree and makes a mouse-sized grub that bores throughout the tree, eventually killing the host altogether. The beetle requires an open wound, such as from a freshly cut limb, where it inserts its ovipositor hypodermic-style into the cambium and extrudes its eggs. No small feat, as all of our desert trees are very dense and hard even to saw. Obviously, this is not a relative of the subject weevil of this thread.

Gene

[MattyB]

Here's the pics. I had turned the Agave over a few minutes earlier before snapping the pics so all the grubs retreated to deeper tunnels so I didn't get a pic of how many there were, but there was a lot.

[MattyB]

Can these things attack palms? I keep seeing these holes in the crownshafts of one particular Royal palm.

[DoomsDave]

Can these things attack palms? I keep seeing these holes in the crownshafts of one particular Royal palm.

That is a good question!

I'd treat it with a systemic bug killer and hope for the best . . .

[MattyB]

Just got a response from CDFA:

Hello Matt

Our Biosystematist in Sacramento sent me the following information in response to the picture you submitted:

This is definitely not one of the palm weevils; the adult in the photo is too small and palm weevil larvae lack the two horns at the end of the abdomen in the picture. It is, as Mr. Bradford mentioned, probably the native agave snout nosed weevil, Scyphophorus acupunctatus (Coleoptera: Curculionidae).

Thank you very much for your submission to California Department of Food & Agriculture Exotic Pest Hotline, we appreciate your assistance in protecting California agriculture.

Best Regards

Vanessa

CDFA - Exotic Pest Hotline

Pest Detection/Emergency Projects

800-491-1899 Hotline, Press 0 for an operator

[Stevetoad]

Can these things attack palms? I keep seeing these holes in the crownshafts of one particular Royal palm.

hey matt, the place i used to rent years ago had a king palm that had holes in it that i thought were from wood peckers. then one day a caught a carpenter bee coming out of one of the holes. maybe thats what it is? the palm is still there and this happend about 7 years ago so i doubt its a real threat.

[MattyB]

Cool. I have a bee box for carpenter bees. Maybe they will colonize it next year.

[tank]

Had an agave weevil problem a couple of years ago. Luckily I noticed the holes before any of the plants went into decline. Out of about 20 infected plants I was able to save 16. I used the Bayer systemic soil drench. All of the plants that died were on the small side. I did have one 5 ft A. weberi "melt" but I guess the grubs left enough of the heart so as to not kill the plant. It has since recovered, although it took a few years.