Sunflowers under attack?

[GardenGnome]

Hello all!

This is the very first time I have tried to grow sunflowers, and to the best of my knowledge no sunflower has been grown within 250 feet of my garden for over 15 years. In other words, I don't think there are any persistent sunflower pests that have been hanging around waiting to have a go at the plants.

I got my seeds from Scheepers Kitchen Garden Seeds, so I think the seed quality is good. I've used SKGS for other seeds and never had any problems with them.

I planted six American Giant Sunflowers and four of them were utterly destroyed, down to the ground. I put cages around the other two, but damage continued. I am wondering if the plants are being hit by insects of some sort?

I've got a thick ring of diatomaceous earth around the base of the two remaining plants now (not visible in the photos below), but I think it may be a bit of too little, too late. In any case, can anyone help me identify what critter did this to the sunflowers, and how to get rid of them?

Any ideas and suggestions are very welcomed! I was really hoping to see some tall, yellow sunflowers this year, but it's really looking like I'll be lucky to have a single plant survive to three feet...

GG

 

[MoreRootsMoreFruits]

Some of the bites look circular like something with a flexible neck is nibbling from side to side as it sits there maybe. It looks like the damage is starting at the leaf edge. Seen any caterpillars or butterflies/moths knocking around? Any slime trails?

Could it be sawfly larvae?

 

[GardenGnome]

Not that I've noticed, no. I will keep an eye out for that, though.

 

[MoreRootsMoreFruits]

Sawfly larvae? maybe check under the leaves for eggs/pods or something similar. They could have moved on by now I suppose

 

[Oliver Buckle]

I would expect slugs, go out with a flashlight late evening. Most daytime things would be obvious enough for you to have seen them doing that amount of damage, but big slugs at night just leave you with the devastation. Partly they find newly planted things because you water them, they can smell water and head for it.

 

[GardenGnome]

I will head out later tonight and see what I see!

While I was doing some watering this afternoon I did notice a couple ants on one of the sunflowers. Could ants do this kind of damage?

 

[MoreRootsMoreFruits]

leaf cutters might but slugs do like a juicy leaf especially if the ground gets dry it seems and it's amazing how many can hide out in the day and then appear at night. Armies of them where I live! I heard bran is good for deterring them by interferring with the slug's digestion, don't know if it's true though. Pellets are harmful to other creatures besides the slugs so I avoid using them

 

[GardenGnome]

So, the enemy has been found! I just came back from a nighttime patrol of the garden and the remnants of the sunflowers were covered in small, reddish– brown beetles. An Internet search for "small brown beetles" is rather unhelpful since there are so many results, but I did manage to capture a few of them. I'll get some pictures put up later, but if anyone knows of small, reddish– brown beetles that like to feast on sunflowers, please let me know!

 

[MoreRootsMoreFruits]

Right, I nearly said beetles as there seems to be a few that are found on sunflowers but I didn't think they'd leave that size of bite marks and you'd often see some slime if it were molluscs.
Intrigued to see what they are and if you can't I.D. them a local Massachusetts University Entomologist would probably be able to.
Be careful if it's a type of blister beetle though;

Blister Beetle

Question: Hello. I found this bug on my Quince today. I was worried it might be an Emerald Ash Borer, but seems to not be that. The head is shiny emerald green, though. Could you please let me know what it is, and if I should be concerned? Thank you. North Andover, June 2014 Answer: It is an...

ag.umass.edu

 

[MoreRootsMoreFruits]

Until I see one I'm going to have a stab in the dark at the japanese beetle or colorado potato beetle larva?

 

[Oliver Buckle]

A search for 'Sunflower nocturnal beetles' brought up several, including a 'Sunflower beetle'. Glad I suggested taking out a flashlight. Colorado beetle would be bad news. Maybe they are a bit more common in the US, but here they are reportable by law, and pretty well eradicated, I remember seeing one in France when I was a teenager. Still, you now have a target, good luck, and I hope it is not too late in the season to still have your sunflowers.

 

[GardenGnome]

Behold, the foe! I have no idea what they are, but it turns out there is a fairly large sunflower farm five or so miles away. I'm going to chat with their grower when they get in, but that won't be for a couple hours. In the meantime, I present... the beetles!

 

[MoreRootsMoreFruits]

Who's that Paul and Ringo? Yeah that's a good idea.
Looks similar to a couple on this page if you scroll down especially the triangle behind the neck. The 7th and 8th picture down:

Beetle Log (NEW!)

June 16, 2016: Short day trip to Cuyamaca Rancho State Park to check on the Poodle-dog Bush. The Poodle-dog Bush ( Eriodictyon parryi ) is flowering in a huge way again, after several years of...

www.beetlesofcuyamacamountains.net

 

[Chuck]

Behold, the foe! I have no idea what they are, but it turns out there is a fairly large sunflower farm five or so miles away. I'm going to chat with their grower when they get in, but that won't be for a couple hours. In the meantime, I present... the beetles!
View attachment 91728
View attachment 91729

That is a June Bug. Google June Bug images. Very common just about everywhere and they eat just about anything. They are the cause of the grub worms that eat the roots of lawn grass.

 

[MoreRootsMoreFruits]

Similar to a June Beetle