Unfortunately, I think grocery store veggies can have Bt in them - maybe somebody else knows the answer to this for sure.
Can you buy some dill, fennel or parsley at a nursery? I've found the nursery stock to be okay.
Or do you have mock bishop's weed or some other natural host growing in your area?
Sherry

Sherry, that puts me in mind: What do the May-season BSTs do in the wild? Queen Anne's Lace isn't sufficiently grown yet. They must feed on something.

But I'll try the nursery. I also have a parsley plant of my own, so between the two we ought to do OK.

Jeff

My dad and I use Rue for the BSTs. His rue is a nice mound about half a foot tall, and 2 feet wide. It is a perennial as well.

Jeff, down here, they eat mock bishop's weed, a weed in the carrot family that looks like dill and fennel, but I don't know what they eat in MD.
I raised a batch of BSTs that I found on dill plants at a local nursery. The nursery owner appreciated me taking them off her hands, so she sold me the additional dill plants I needed for a reduced price.
Good luck - I hope you find a nice nursery owner like I did!
Sherry

The only problem with purchasing Rue for immediately available food, is that the nurseries don't consider it a "food plant", so often it gets sprayed with insecticides. Lisa had a problem with that one year and all her cats died as a result. Rue is only used as an ornamental herb, altho it does have medicinal qualities, but it is not recommended that it be used as such without a greater knowledge of its potential harmful effects. It is not a culinary herb.

Most fennel and other culinary herbs, such as parsley and Dill are kept isolated from other plants as nurseries and not sprayed with chemicals. However, there is no guarantee that there will be no drift from plants that ARE sprayed either.

It's a dilemma, I know, and decisions aren't easy on the issue. In planning for next year, you might consider adding some Zizia plants, which are native forbs found in the US. I am so glad I have mine so the cats move to that (planted next to the Fennel) as a backup. It is a perennial also. Not their first choice but readily consumed when necessary.

Susan

I didn't know anything additional about Rue, we only use it for getting BST cats. The nursery I got mine from keeps it with everything else, and they claim it is not sprayed.

Golden Alexanders are growing like weeds somewhere in Maryland. Mine are huge right now (and flowering so they are easily recognized). I could feed an army of BSTs but I'd settle for one right now.

Here is a link that might be useful: Golden Alexanders

I have the Heart Leaf Alexanders, Zizia aptera. I love them. I have never found an egg on them, but the cats move to them when the Fennel is gone (it is planted next to the Fennel). I have so much Fennel this year. I have 3 big Bronze Fennel, and 3 huge Finocchio Fennel planrs, tons of Dill plants, Rue, and Zizia. Guess what? Not a single BST seen yet this year.

Susan

kcclark: Yes, that's what I ended up finding. I thought it was Hemlock, but the leaf looks more like Golden Alexander. It's really leafy! (Which is a relief, since dill and Queen Anne's Lace are *not*).

They're all happily munching now.

Thanks, all.

Jeff

P.S. I went to Home Depot and no-one could tell me whether they use Bt with their plants.

Very glad to hear that, Jeff.

I grow dill because the mama BSTs seem to prefer it and it is easy to spot the eggs/cats on it. I grab the cats and finish raising them on the Golden Alexander. The bigger leaves are a big plus. In the 2 years I've had GA, I have not found a BST cat that refused the different food. During the many years when I would switch BSTs from dill to QAL or parsley, I don't remember ever finding fussy eater either.

KC

I think grocery parsley should be ok - just wash it off ahead of time.

I came home and found my first BST caterpillars of the season on my Rue!! Surprise, surprise, with all the other plants around. This is a rue I planted last year--finally found a spot it likes. It's blooming and doing well.

I love the zizia for a back-up, and the caterpillars get bigger on it than on the dill or fennel. Good food source.

Sandy

Okay, Rue is in the Rutceae family. This is the same family as citrus plants. Dill, fennel, zizias, hemlock (water and poison), queen anne's lace, carrot, etc. are in the apiacea family (also known as the umbilliferae). BST will lay on almost anything in these families. I have seen them laying on water hemlock. Many studies have been conducted on their behavior in regards to these plants. Females are looking for levels of furanocoumarins in these plants. These compounds are found in both families (which interestingly enough, it is thought that one or the other groups of swallowtails split off of one group to utilize a new family of plants). I have talked about this before and some of this is for newbies. Furanocoumarin is the chemical that causes a photodermalogical reaction. If you get rue "sap" on your skin and are exposed to sunlight, you will end up with a nasty rash. The levels in rue are sooo much higher than in the other plants (except maybe cow parsley, another you don't want to mess with). So, BSTs don't do as well on rue as they do on the others. Some is good, a lot, not so good. This is true with milkweeds, cardiac glycosides, and monarchs as well, which is why some are preferred to others.

In regards to host plants, there are lots of native species that BSTs have used in the past. However, many of these senesce during summer. I can't remember, but I think zizia does tend to do this. BSTs have been changing their behavior with the introduction of fennel and dill that now grows wild. They are utilizing these plants now and I believe having more in flight periods. I need to find that article. However, some native plants are helpful as these are what the butterflies evolved to use in the first place. So, look at some of the native plants in the apiaceae family. The USDA Plant database is helpful.

Good luck Jeff!
-Elisabeth

Cheers,
Elisabeth

Very nice discussion, Elizabeth!

Larval host plant preference varies from region to region. Possibly even more narrow area than that. I have never found a BST on Queen Anne's Lace here in OKC, for instance, and I have absolute tons of it in the back yard.

I think the BSTs might prefer Dill here, but Dill is very short-term in OKC. When it gets hot, it's pretty much done. Fennel lasts longer in the heat and even it doesn't like the heat, bolting very quickly once the days get in the 90s and nights in the mid to high 70s. Once the flowering begins, the foliage becomes thin and sparse. Rue tends to tolerate our heat the best of these two. Zizia is okay, but stops growing during the heat, and the leaves tend to get tough. Despite this, the BSTs will eat it when other food is lacking.

I'm sure that in different climates and locations, other preferences may be observed.

To me, the value of having Rue in the garden is that it attracts two different Swallowtails - Giant and Black.

Susan

I have two kinds of wild native parsley. I saw a BST checking them out a while back, so will have to check them again...so far have seen no eggs or little cats. One is seeded out and little fresh foliage left, the other is fine.