Beneficial Insects

calico20hill

Thinking ahead to full bloom time, and topic of beneficial insects that eat the insects that damage our blooms....Has anyone tried interplanting dahlias with plants that attract beneficial insects to them and did it help reduce insect attacks on your dahlias? I try to keep my garden as organic as possible but have had problems with several kinds of flying insects that eat on the flowers. I was just looking at advertisements from a seed company for plants that attract the beneficial insects, and wondered about integrating those plants right into the dahlia beds. One of them was the wild carrot or Daucus (Queen Anne's LAce)That grows to about the same height as the dahlias. If you have, how did it work out for you and what other plants might bring in the good guys? IN particular I see a lot of Soldier Beetles(?) BLack bugs about half an inch long that chew holes in petals. My ducks will eat the slugs and other ground level bugs but I am thinking about the taller plants. What else should attract the good bugs ?

PNWGal

calico20hill IN particular I see a lot of Soldier Beetles(?) BLack bugs about half an inch long that chew holes in petals.

Soldier beetles are good guys, and eat the bad bugs, not plants. Ours are narrow, with black bodies and red heads. Can you get a picture of the black bugs chewing holes in your plants?

KitCMC

Queen Anne’s lace is very invasive - I would think long and hard about planting it. Our last garden had Queen Anne’s lace, gooseneck loosestrife, and Allium tuberosum - all planted by the previous owner for some inexplicable reason. I spent hours trying to manage all three instead of using that time to care for plants I wanted in the garden. I do live in natural prairie habitat, but I can’t imagine it’a so much better behaved elsewhere.

PNWGal

KitCMC Queen Anne’s lace is very invasive

I will vouch for that. It was growing in the parking strip where I made a dahlia bed. The hoverflies especially love it so I left some for them, hoping I could have just a few plants if I kept them deadheaded. A nice thought, but it was impossible to keep up with the prolific and fast maturing seed heads. At least the seeds are heavy enough not to blow around, so the patch was reasonably contained by being surrounded by pavement. But it would be out of control fast in your rural setting. If it were native I could live with that, but it isn't. It's on the Washington list of invasive species, and on a list of problem weeds at OSU.

Krista

KitCMC Oh I missed your comment about Queen Anne’s lace, we must have been hammering away at our comments at the same time. I grew up in southern Indiana and remember loving it in our horse pastures. It didn’t occur to me that it would be invasive here in WA so, thank you for this reminder! Nixing it from my list unless I can find a hole surrounded by cement like PNWGal.

Krista

I like this thread a lot, I’ve been thinking hard about this topic in particular. I try to avoid pest control that isn’t organic because I tend to rotate annuals through my beds, flowers and edibles, since my space is so small. I’m considering purchasing beneficial insects but I’d prefer attracting my local good bugs instead of bringing in species that aren’t indigenous to my local area. I’d like to learn more about how other folks support soldier beetle populations. I do love Queen Anne’s lace so I’m adding this to my list now.

Last year I planted lots of various basil varieties at the feet of my dahlias, and planted gem marigold as a boarder in front. I also planted nasturtium, calendula and cosmos which acted as sacrificial plants very successfully. I am a super novice on this but here’s the list I’ve been developing for this coming year. I’m really looking forward to learning more.

Basil: repels thrips
Garlic: repels aphids, thrips, spider mites
Cilantro: attracts: parasitoid wasps, hoverflies, ladybugs, and lacewings. Repels: aphids, flies, spider mites
Yarrow: attracts ladybugs, lacewings, hoverflies, soldier beetles

Susceptible to powdery mildew
Four O'Clocks: repels Japanese beetles

Trap plants:
Chives & oregano: thrips trap plants
Nasturtium: aphid trap plant
Marigold: thrips trap plant, also attracts soldier beetles

attracts snails & mites

Juliarugula

Krista

And yes! Blooming Cilantro is amazing at attracting beneficials - I forgot that one! We don’t have much of a cilantro season here - it’s tiny tiny tiny and then bolts. But I grow it just for the bugs.

Juliarugula

I don’t really interplant, but I try to keep an insect friendly garden, never spray pesticides, and occasionally purchase beneficials to add. Most likely, our insect life is pretty different due to our location and climate, but I have noticed a few things that might be helpful.

Predatory wasps seem to loooove my celosia. Definitely their favorite.

Regular wasps are pretty happy to eat caterpillars also. I’ve discovered over the years that if I’m having a minor caterpillar invasion I can snip several caterpillars in half on the plant to attract wasps to the location. It’s kind of fun to watch. (Sorry if that’s too grotesque!)

The only thing that really seems to help much with Japanese beetles seems to be to remove other attractive food sources and bag blooms. I had a rose nearby that they loved and have had less of a problem with them on dahlias since I took that nearby rose bush out.

Krista

Juliarugula It’s also helpful to hear about your positive results with your rose bush removal. I’m on the fence with trap plants, if/how close to incorporate them? I’ve got gladiolus planted quite near my dahlias and I’ve yet to come to terms with the fact that they should probably go. I think they’re so pretty but I’ve read they’re a major attractor of thrips.

Krista

Juliarugula Great idea leaving bait behind for your wasps! I snip slugs in half with scissors when I’m on patrol in the evenings. I used to walk around with a headlamp on, scooping them into a little to-go tub of soapy water but then I found myself encumbered with a bucket of soapy slime to dispose of. I’m sure my neighbors are puzzled when I’m out in the garden after dark.

Cilantro always bolts on me too, even with our temperate summers. It’s been impossible for me to figure out how to have it growing at the perfect stage when I’m ready to use it. I’m very glad to hear it works for the bugs, I’m hoping to broadcast some closer to the dahlia this year.

Dahlia53

Krista the nice thing about cilantro is that once you have it, it interplants itself in the dahlia beds and is slower to bolt because the dahlias shade it out and if one is lucky you get another fall crop in sept. i eat it even when it bolts but try to leave most for the beneficial insects. chamomile and pineapple plant (chamomile relative and it smells like pineapples) also good for attracting beneficials.

calico20hill

Darn, I had forgotten the invasiveness of Queen ANne's Lace. Good reminder! I do love the dark version of it in bouquets but now that I think of it it grows wild all around here, but really runty since it is growing in the hard dry clay....and even that doesn't faze it!

MY worst pest Is... I think they are called Soldier Beetles, or something like that. ...Bigger then Lady Bugs and longer bodies. Its been a while since last summer and I can't remember exactly. I have absolutely NO problem with slugs but the ducks can't reach the upper parts of the dahlia plants so " fly in " bugs evade them.

If we ever get it done, there will be a perennial border on one side of the dahlia garden with lots of plants chosen to encourage butterflies and birds. I imagine a few of the dahlias might get nibbled by the larval stage of butterflies. I hope it all balances out.

Emilyp

calico20hill I use cilantro, dill and sweet alyssum for my beneficials, along with all the other annuals I grow. I release minute pirate bugs and green lacewings, and it has worked wonderfully for me in zone 5. The minute pirate bugs will give me a little nip now and then, but boy do they do a good job in the dahlias.

Krista

Emilyp I know our zones may make a difference, but when are you releasing the minute pirate bugs and green lacewings? I’m still considering bringing bugs in but I’m not sure when the best time to release who will be for bets results.

dahlia1972

Emilyp Do the lacewings eat the pirate bugs or vice versa?

blown_dry

If you have a mildish climate, fennel can also be an issue. It's a big problem invasive around here. I planted the bronze version in my garden and it's really hard to eradicate.

Krista

blown_dry in Seattle, garden varieties of fennel grown as a vegetable for their bulbs and foliage are different from the invasive varieties that are sown for pollen. Are both invasive in CA?

PNWGal

Ah, yes. The parking strip across the street is all bronze fennel & lemon balm. There is a stretch of bronze fennel growing wild along the railroad tracks too. Are annuals perhaps a safer way to go than perennials?

MissyWeitzel

I'm planning to do sweet alyssum, dill, and yarrow in planters around my beds. I have a lot of established yarrow in other areas so I'll just divide some and throw it in pots.
I tried using geraniums as a trap crop for the Japanese beetles last year but it didn't work. They love gerananiums and when the beetles chew on them, it paralyzes them for up to 12 hours, rendering them helpless for me to scoop into soapy water, other insects, or the elements. Unfortunately, when placed near my dahlias they decided they like dahlias more. Geraniums in the front yard had a lot of beetles though, so I guess I'll keep them up there. 🤪

Juliarugula

MissyWeitzel I tried using geraniums as a trap crop for the Japanese beetles last year but it didn't work.

My understanding is that’s it’s best to avoid anything that attracts them, even as a “trap”.

I’ve also heard recommendations to instead convince your further-away neighbors to plant the trap crops. 😈😜

addicted

Emily, I am also in zone 5 and have used green lacewings successfully for at least 5 years. I will have to try the pirate bugs as well, but have been delighted with the results of the green lacewings!

Emilyp

Krista I release them once I have an established area for them to live, once I have blooms and cover. I also stagger them, so that they don't eat each other immediately.