Leaf beetles of some sort. Nasty critters. Pyrethrin will take them out, but will take everything else out too - seems to be the best thing though. I've also found that now that I keep ladybugs in my gardens I don't have such a problem with them. They seem to keep the population mostly at bay. I can't remember what I ID'd them out as a few years ago but this may help:

-Marie

Here is a link that might be useful: Links to Beetles

Thanks, Marie. Lord knows I get enough ladybugs IN my house during the off season. I have seen several out there but not nearly enough to take care of my yarrow problem.

I know it probably sounds crazy to some but I really don't want to jeopardize the little toadies in my garden. If I can figure out a better solution I might sacrifice the yarrow. There are so many other plants out there that I can put in it's place that won't cause such grief.

Kristy

I did a little searching online for this bug and cannot find it. That really should be no surprise considering how many pests are out there. I found some organic ideas to try at Mother Earth News and will see if I can salvage my yarrow. I will be trying a hot pepper spray mixed with a liquid detergent-alcohol spray. I would worry a lot less about the toads with this...but I will still be trying to flush them from the area beforehand.

Otherwise, I am a little confused at how a plant that is so well-known for attracting beneficials can all of a sudden be the plant that is being attacked. I'm stumped.

Kristy

I found out what the bugs are on my yarrow and have found that they are not life threatening to the plant. They are called Black-and-yellow-striped Beetles (Poecilocapsus lineatus) but are not actually beetles. Here is a link to an article about them...
http://www.post-gazette.com/pg/06154/695300-47.stm

And below is a picture of them.
Just thought I'd share so anyone else dealing with them wouldn't be going through the trouble to figure them out. It was a chore finding info on them to say the least.

Kristy :)

Here is a link that might be useful: Bug Guide

If the bugs are not life threatening, what is making your yarrow turn brown? Any idea?

I've got yarrow (pink) for the first time this year. It is blooming now and I just love it. I can see why you plant it everywhere you live. Do yours wilt down on very hot days? Mine did on the blistering couple of days we had recently. And it didn't matter if I had them well watered - they still wilted down. Carmellia

The bugs are probably four-lined plant bugs, which are black or green- and yellow, and their larvae, which are red and black. They make brown closely spaced holes in leaves. However, they don't cause permanent damage and will go away. They are slow moving so you can catch some of them.

If the bugs are not life threatening, what is making your yarrow turn brown? Any idea?
Like Clark said, they make small brown holes in leaves which don't really look like holes in yarrow since the leaves are fine and feathery. But it gives the greenery the same brown effect. They don't cause permanent damage but they are finding their way to many of my neighboring plants. So, I hope that whole end of my garden doesn't wind up looking brown for the next month.

I've got yarrow (pink) for the first time this year. It is blooming now and I just love it. I can see why you plant it everywhere you live. Do yours wilt down on very hot days?
Yes, it can get kind of wilty but when it spreads and thickens and becomes more established the heat seems to be less of a problem for them.

However, they don't cause permanent damage and will go away. They are slow moving so you can catch some of them.
Thank you, Clark. Yes, they are very slow moving but I hate to say that I am really outnumbered. I could spend days out there collecting them which is why I'm opting to try a homemade remedy on them. If it doesn't work I may just crop the affected plants back and let them grow out as these pests lives wind down.

Kristy :)

I'd avoid spraying anything on your plants if you're worried about harming toads. Detergent-alcohol-red-pepper would certainly harm them. Amphibians' skin is very sensitive.

I never spray for bugs. Usually the predators find them and things sort of balance out. Wrens and wasps love small bugs. I like your idea of cutting the plants down. Denying the pests a food source is probably the best way to kill them off. Bugs usually have a set, timed lifecycle.

Thanks, John. I have given up on the spray. For now I am paying my two kids $1 a day to stroll by and pluck the bugs off and toss them into a bucket of soapy water. They have been having a lot of fun with it...they think of it as an Easter egg hunt.

I will probably be cropping down the plants they've affected after my kids have had their hey day with it.
Kristy :)