I don't think they are harmful, if organic solutions are used.
Hot pepper may work.
Another option is to avoid the most deer vulnerable plants altogether while growing other more deer resistant plants such as Milkweed.
Growing wood nettle (stinging) as opposed to False Nettle will deter nibblers of all kinds as well.
I deal more c rabbits. What they leave alone (Not much!!) includes Anaphalis, Clethra, Joe-Pye Weed, Swamp Milkweed,
Goldenrod, and Antennaria.

Deer ate the Joe Pye, goldenrods, sunflowers. At least that was in the early summer. Then i sprayed, but I noticed the insects avoiding the plants after that. Don't want to have conflicting situations.

Thanks for your comments.

Ouch!! I can only vouch for the bunnies, thankfully no deer in my backyard. Just bunnies and lots of those Japanese Beetles.

I have no experience with this but have heard from severals that it works for 'them'. They take 2 raw eggs and crack them in their 1 gal sprayers. Shake well and spray plants. I guess it works for a couple weeks or the next rainfall. YMMV.

SCG

We have found that Liquid Fence works the best. The main constituent of it is rotten eggs. My guess would be that for nectar plants the spray would not make too much difference. The butterflies are going inside the flowers anyway. In terms of caterpillar food plants, I have no idea. The deer are the bane of my existence as well. Frankly, how much worse off could the butterflies be if you spray? If your neighborhood is anything like mine, without spraying there will be zero for the cats to eat.
Liz

Someone at the workshop said that pepper, in some of the sprays, is not good for bees. I am worred about all pollinators .After I sprayed early in the season, all insects avoided the plants for several weeks. Now I just spray the foliage

I have used Liquid Fence but prefer I Must Garden. It appears to last longer, through more rainy periods. It also smells not quite so bad...has cinnamon, mint, and lemon grass oils as well as the eggs and garlic, of course.

Don't want to hurt the wildflie. Here we only kill copperheads when they get close to the house. Unfortunately, this year our dog was "fanged" on the nose and has had extensive vet treatments and medicine.

The cost of living in the woods. Thanks for all input.

I have some deer, though my garden is up near a somewhat busy rode. They definitely munch on any aster. But, I've grown tons of zinnias for the pollinators and they haven't been touched. Also Agastache, penstemon, columbine, rudbeckia, milkweed (tuberosa, syriaca, incarnata, curassavica), snapdragons, salvias (annual and perennial), sedums, lavender, tithonia, chives, oregano, etc. I hope some of these would help enhance you enjoyment of your garden without sprays.

Martha

I am mainly into natives, so I haven't tried a few of the plants you mentioned except for A. curassavica. That is a WOW plant. I am collecting seeds to try and keep it going since it is somewhat tender.

I planted one type of Agastache in a different location, and the deer got it, too, but based on your advice, I will try more. Thanks for your ideas!

Ncrescue,
I just purchased two White Snakeroot plants in August. They are native here in Michigan and grow in shade. Mine were swarming with pollinators as soon as I put them in the ground. They do have a reputation for rampant reseeding, but that isn't a problem for me. The plant has just gone to seed and I grabbed a handful to wintersow. Would you like me to get some for you? Anyone else who would like some is also welcome. Reply here or send me an email.

Martha

Thanks. I have that one up in the mountains but have only brought down two for the Piedmont region. Also, I like diversity, so yes, please send. (Will send address directly.)

I am going to the mountain in a week, with the hopes of collecting seed. Hopefully, the critters will have left me some. Usually, there is Chelone, Joe Pye,and one DYC that are ready. The milkweeds, alas, will be long gone by then.

Ncrescue,
Do you need milkweed seeds? What variety do you need. I plan to go out today to harvest common milkweed, and I'm waiting for tuberosa pods to ripen. I already have some incarnata seeds fresh this year and some left over from last year. If you'd like any of those, let me know. I also put out an offer of Liatris ligualistylis and got lots of responses, but haven't received any postage from anyone. So, if I send out a package to you, I'll include some of those as well. I'll send you my address.

Martha

Try not to use any chemicals-even the ones claiming to be organic. We paid Good Nature good money to treat our large lawn with organic stuff-garlic and oil-then the next day we found our butterflies were incapacitated with those products-they were trapped in the oil -their wings ruined. We had no butterflies or moths for about a month til that crap got washed away! I too worry that deer spray is affecting our insects.

Gosh! Has it been seven years since this post started?? The only things I have been spraying in the last few years are my native lilies, if they are in bud or bloom, and a few of the special Trilliums. Otherwise, I have decided to let nature handle all of this. It makes sense that excessive oils would harm butterflies. I think the only answer is to plant so many things that the few things deer eat will not be missed.