We had the same problem with our broom. You'll probably go out and see little caterpillar bodies hanging from the branches, kind of creepy. We've had to spray twice this year. BT works too. Just prune the broom a little; it will grow back pretty quickly. The redbud damage doesn't sound like the same culprits did that. Maybe grasshoppers?

If the other bites are round or semicircular, it's most likely due to a leaf-cutter bee.

If so, it's a beneficial insect. In that case, leave it be. The missing circles won't damage your plant other than being interesting geometric cuts.

Sounds like leaf cutter bees to me too. They love redbuds and mine looks the same way every year.

Why are you spraying with pyrethrins? Just for the record, blind spraying doesn't do much good. Most insect sprays only work on contact with the insect and have little, if any residual effect.

wanda

I think this year is the year of leaf cutter bees.... why not just pick the caterpillars off instead of killing every decent bug around?

THanks for the info on the leaf-cutter bees -- had no idea about them. I understand they're a beneficial insect and I wouldn't dream of harming them. I was surprised by how many holes they made in a fairly young tree and was concerned for the tree.

Unfortunately there's no way I could pick that many caterpillars off the broom bush -- it was completely covered and they'd started to get into the neighboring acacia. I won't spray pyrethins indescriminately, but only where there's a problem.

Thanks for everyone's feedback and advice!

I just did a quick search - broom caterpillar -. There were a few hits, one recently in the Butterfly Garden forum had a nice picture of the bug. Other hits had some more advice on how to treat pest caterpillars.

This site is great. I would search here, google if need more info to form a plan of action. Or not, I mostly just watch. Except for snails and slugs. They must die. Off topic but I moved an oak leaved hydrangea that was plagued with snail damage, now it has none. The slugs in that area don't know how yummy hydrangea leaves are? The shade in the new spot is better for the plant? Hope it survives its new nemesis, dogs chasing squirrels.

Oh, I searched for leaf cutter bees, one article did say they can be a problem if they remove a lot of leaf area. Spraying doesn't work against them as they don't eat the leaves but use it for nesting material, must cover the affected plant. One poster wrote a bee kept putting leaves into her husband's gardening shirt pocket. Think I will have to sit out with my binoculars next spring to try to see one in action. Thanks for the ID on the redbud leaf cutting!

I put sprinkled Sevin on my Brooms and I no longer have a problem. They definately love munching on them. And I have been caterpillar free for a week now. I also did pick alot off before I sprinkled. But i think i've lowered the problem down.

Broom plants are highly invasive weeds that are smothering biodiversity in our wildlands (at least out here on the West Coast). The best, most "eco-friendly," option would be to remove the broom plants and replace with natives or a non-invasive exotic species. To boot, pyrethrins (despite being of natural origins) have been found to be lethal to aquatic life and should be avoided at all costs.

Overall, I wouldn't waste energy (or risk my health and environmental health) by using toxic pesticides to protect a plant species that demands thousands of volunteer hours to remove in our parks/wildlands.

Recently, local weed-warriors have discovered caterpillars girdling broom plants out in Marin County... until we learn better, this is good news! Invasive plants tend to do so well because they lack natural predators/controls. We'll keep our fingers crossed.

Instead of trying to kill these caterpillars, you might have done better to take the little heroes (or the whole plant) up into the nearest open space. "Horrible" broom plants are taking over countless acres -- and obscuring trails and creating fire hazards -- crowding out the native plants that have been there for millenia.

By the way, which species of broom was it?

BT is a far less toxic approach to caterpillar management. It kills caterpillars and nothing else.

But all those pesky little caterpillars are baby butterflies or moths!!!

For me it's the gophers that must die! And cockroaches.