The caterpillars you've been killing are almost certainly those of the black swallowtail butterfly. Most consider both the caterpillar and the butterfly beautiful and would cringe at the thought of someone killing them. Their caterpillars do minimal damage (or so has been my experience) so leaving them on the plants won't really hurt anything.

As for carrot rust flies, you won't notice much in the way of damage (aside from maybe a few yellow leaves) from their maggots until you pull the carrots and find holes/tunnels in them. I grow under row covers to prevent them from causing problems.

Rodney

I am very sorry for killing these. I shall stop now! I never meant to do damage to beautiful creatures. I absolutely hate killing insects but for those that cause damage to my babies food source. I will no do anymore harm to these guys...

Keith,

I have also had the black swallowtail on my fennel plants. They did very little harm, and my son found them so much fun that I had to make a "no petting the caterpillars" rule.

My usual mistake with carrots, as well as other things, is not thinning enough.

Yep ME2!

Is it too warm/late in zone 6a to start another crop of carrots?

I just check Johnny's website. Germination starts to drop off when temps get higher than 77 deg F but the planting guide is early spring to mid-summer. I will be planting more carrots to have as a fall crop. Johnny's just emailed a notice that it's time to think about planting seeds for fall crops. Our nights here in NH are still cool but we usually get a heat wave around July 4. Keep row well watered. Lower germination might mean less thinning required LOL.

Chris - Probably late July is the time to plant carrots in your area for a fall crop (which produces sweeter carrots than those grown in spring/summer anyway). The key to seeding carrots in the summer heat is keeping the soil moist during germination. I first water the seed bed well the day prior to seeding, then sow the seeds, water again lightly with a misting spray can so as not to wash the seeds out and then cover with cardboard to hold in the moisture. Check for germination after about 5 days (misting again if soil is drying) and everyday thereafter and remove the cardboard when you see the seedlings popping up. Summer sown carrots germinate much faster than those sown in the cool spring.

I planted carrots in early July last year with no issues. They had extreme cold tolerance -- they didn't blink with lows in the teens. You will definitely want to keep them well watered until they get going.

Thanks! I will definitely be sowing some more then.

The past couple years I've grown carrots I let them grow from spring all the way until the fall( I forgot about them). What I ended up with was massive carrots, and I know the general rule of thumb is that they taste better when picked smaller, but these were still very good.

Reports of things not tasting good if you do something wrong that you find on the Internet are usually grossly overstated :)

I usually sow two or three times a summer, to keep a fresh supply rolling along, and to outwit carrot rust fly. I have not noticed that taste is affected by temperature as much as a regular water supply. Johnny's shows best germination at SOIL temp of 77 degrees. My soil is just now getting to that temperature, cold nights until early June. When I forget the carrots (and yes I have done that too) I just consider them cooking carrots, instead of raw eating.

Oh and since we are talking carrots, does anyone have advise on Meridia? Territorial puts it at 240 days. I had the overwinter once, mostly by accident, and I would really love to figure out what I did right. And do more of it!

If I plant them in the fall, do I want to see them germinate, or not? How large do I want them to get? Leave them under snow (that is what the Accidental crop had), or put them in my unheated greenhouse? Territorial is in Washington, I think, and I am in MA (I know that one...) so would I still plant in September with a Halloween first frost guess? Cover, mulch???

thanks for correcting me that it's SOIL temperature not air temperature to consider. A quick read says Merida is slow to bolt so that's why it's good for overwintering but the trick seems to be using enough mulch to keep the ground from freezing. I have a homemade high tunnel and although at night it gets as cold inside as it is outside, the ground doesn't freeze. I have not tried carrots in the high tunnel so thanks for bringing this up. I might try some this winter.

Thank DeFrost! The winters here are nothing if not variable, and I think the year Meridia gave me four large carrots in the spring was one of the milder versions. I had planted them in an old compost location, and mulched. If I can work out the mole/vole problem I may put the resident engineer to work on a shelter for the bed that currently has garlic, and broccoli in it for the winter crop.

Any suggestions on how big I want them to be by short days for best survival?

I have both of Eliot Coleman's books about gardening year round (he promotes high tunnels and market gardens in Maine) and still can't figure things out. There are various planting calendars around but I'm still confused. Our high tunnel is wood framed with peaked roof (wood was easier and cheaper for us than hoops) covered with greenhouse plastic. You might find some info on Johnny's website. One of my mistakes is not watering enough even though my husband installed a yard pump in the high tunnel. So that slows down growth. Keep in mind everything goes dormant during the period of shortest days and starts growing again when there is at least 10 hours of daylight. Hope others chime in. You might re-post question on the forum about Four Season Vegetable Gardening.

I have one of Mr Coleman's books, and a tunnel as well. I also have a lack of clarity about calendars, but I have had some success using the tunnel to protect crops from the drying effect of the cold air especially in limited snow winters. The biggest surprise was the leeks I rescued from under a collapsed, iced over section. After we got the ice and plastic out of the way we had a generous leek crop, despite having done most things wrong. LOL!

Thanks for the tip on 4 season forum!! Didn't know we had one. Sheepish face!

There's not much activity in it but there's one guy who has a lot of experience who might answer. I've actually found the high tunnel great for tomatoes in summer. They didn't get the diseases the ones outside did. Sides are rolled up but they don't get rained on.

Do you mulch them inside tunnel? I had problems with blight last year, and am experimenting with a few in my UGH (unheated greenhouse) .

Pulled a few Napoli and Cordoba to thin and check, yep they are making carrots! Oops I saw carrot rust fly on 2nd planting, have to dig up the sugar and coffee ...