An important top ten list for the year: Important host plants for butterflies, moths, and birds

We all love a list, I think, as long as it is not a list of chores to be done. Particularly fun at this time of year is a list of plants we wish to add to our gardens in the season ahead. I have lists of seeds I want to grow, lists of plants I want to move, and lists of projects I want to tackle in the garden.

Last week I came upon a list that made me sit up. It was first published in 2009, and I wish it were better known than I think it is. Douglas Tallamy, professor of entomology at the University of Delaware, published a study describing the impacts of planting nonnative genera in the garden and in the urban/suburban landscape in particular, on insect populations and the implications for life up the food chain.

I am embarrassed to admit that, while I believe in and use organic gardening principles and try to employ conservation methods for pollinators, I had never given much thought to the larger ecological interconnections. I’m growing Asclepias (milkweeds) this year because I’m concerned for the welfare of Monarch butterflies, and every little bit of effort helps. I try to relax when I see caterpillars making feasts out of fresh green leaves, because I know those caterpillars will grow into moths or butterflies. And those guys will pollinate my plants, plus they’re pretty to watch. papilio polyxenes caterpillar on bronze fennel

But they might not grow up to be butterflies. They might get eaten by hungry birds instead:

“…a single pair of Carolina chickadees needs to bring 6,000-9,000 caterpillars to the nest to rear a clutch of a half-dozen nestlings. Black-capped chickadees probably need more. If you want the birds, [Tallamy] says, you need the caterpillars, and to get the caterpillars you need the right trees.”  

Songbird populations are on the decline nationwide due in part to the inclinations of housecats let loose in the garden for the day.  Compound that with habitat loss due to development, climate change, and the additional pressures presented by landscaping choices (however benign the intentions behind those choices may be), and it adds up to substantial challenges coming from all corners.

Tallamy’s list uses Lepidoptera (butterflies and moths) to stand in for all herbivorous insects, because data on them are plentiful and they represent a substantial food source for birds. But understand that if you have these plant genera in your garden, they’re benefitting more than butterflies and birds.

What beneficial choices can gardeners make to help sustain not only pollinators, but birds as well?

Ten best genera for hosting butterflies, moths, and the life they support:

  1. Quercus (oaks): 532 total Lepidoptera species
  2. Prunus (peaches, plums, cherries, almonds, etc.): 456 species
  3. Salix (willow): 455
  4. Betula (birch): 411
  5. Populus (poplars, aspens, cottonwoods): 367
  6. Malus (apples and crabapples): 308
  7. Acer (maples): 297
  8. Vaccinium (blueberries and cranberries): 294
  9. Alnus (alders): 255
  10. Carya (pecans, hickories, etc.): 235

While the ten best all happen to be woody plants, herbaceous plants are also on the list. Tomorrow I’ll outline the best herbaceous host plants.

Consider studying Tallamy’s full list before you begin your plant shopping this spring.

Other resources of interest:

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Planning and planting for monarchs

Monarch Butterfly Danaus plexippus Proboscis 2...

Monarch Butterfly Danaus plexippus Proboscis 2591px (Photo credit: Wikipedia)

Now that fall is here, and life in the garden is beginning to slow down (ever so slightly), I am thinking about next year’s garden.

It’s been a wonderful summer here for swallowtail butterflies. I enjoy spotting the caterpillars that continue, even now, to overwhelm my small stands of bronze fennel (one of the construction workers building our addition said he counted 19 on one plant last week!).

swallowtail butterfly larva

A very hungry swallowtail caterpillar munches my bronze fennel to its core.

But as you may have heard if you live in the US, this has been a bad year for monarch butterflies (Danaus plexippus). Habitat destruction and widespread use of pesticides have contributed to profound declines in numbers over the past few years. In the past, I have tried to grow plants attractive to all kinds of pollinators, but as I plan for Winter Sowing 2.0, I intend to sow and plant for monarchs in particular.

Monarch larvae feed on milkweed (Asclepias sp.), and females will only lay their eggs on these plants. Different species of milkweed are recommended for different areas of the US: Monarch Joint Venture has a map and fact sheet about them.

But migrating butterflies need nectar plants as well. Monarch Watch is a wonderful source of information on ways to help contribute to conservation of this species (as well as other butterfly species), including recommended nectar plants. I think my household may try to become certified as a Monarch Waystation next year (I feel a Girl Scout project coming on).

Photograph of a female Monarch Butterfly en ( ...

Photograph of a female Monarch Butterfly en ( Danaus plexippus en ) on a hybrid Milkweed en ( Asclepias tuberosa en x Asclepias incarnata en ). (Photo credit: Wikipedia)

Many milkweeds species perform well with winter sowing–a technique in which the gardener sows seed in a simple pot or flat and leaves it exposed to the elements all winter long. The gardener doesn’t tend the seedlings until it’s time to pot them on. It couldn’t be easier–so there is little excuse for me to not try to help this beloved and charismatic species recover from the challenges it has suffered.

I hope that, if you garden in North America, you will explore resources like Monarch Watch and Monarch Joint Venture to find out ways you can help. There are wonderful citizen science programs around through which gardeners and homeowners can assist with migration tracking and population counts.  No garden is too small to contribute to the conservation of these creatures.

Perpetual caterpillar season

I had thought the caterpillar season was over.

papilio polyxenes caterpillar on bronze fennel

As I was weeding the blue slope the other evening, I noticed tons of them on the spindly remains of my bronze fennel.

Papilio polyxenes

This is the caterpillar of the eastern black swallowtail butterfly, Papilio polyxenes. There must have been ten or so, ranging from fat ones like these to tiny ones perhaps three quarters of an inch long, on one plant alone.

caterpillars climbing

With any luck, I will have a second chance to watch a chrysalis.

Chatham County Extension Agent Debbie Roos has noticed the same phenomenon in her nearby pollinator paradise garden. By the way, she has a terrific list of butterfly- and bee-friendly plants at this site.

Chrysalis failure and success

I think bittster was right: holes in the chrysalis aren’t good. I have given up hope that this one will emerge.

crack in chrysalis

The chrysalis is getting more and more brittle, and I can see through a small slit that there is something inside, but it doesn’t look like it’s alive.

All the close-up, watchful examination of the site did reveal a successful one nearby, though. At first I thought it might be a dragonfly exuviae (Scrabble word!), based on the ribbed appearance of the end near the stem, but I think it’s just a bit too far away from the pond for this to be likely. It has the thin threads attaching it to the stem, typical of a chrysalis. Also, it seems that exuviae generally survive more intact than this; if it was an exuviae, it has taken quite a beating.

dragonfly exuviae or spent chrysalis?

exuviae or chrysalis?

At any rate, it’s good to know that one of them made it. Wish I could have been there to see it, but maybe next time.

Anticipation

Today I noticed that holes have appeared in the swallowtail chrysalis left on my bronze fennel stalks.

butterfly chrysalis with holes

The chrysalis, which had been an electric green color earlier in the summer, now looks brown and desiccated. I hope it won’t be long before it splits open and we see a new butterfly emerge.

Wildflower Wednesday: Joe Pye Weed

I am not going to win any awards for novelty with this post, but I do love Joe Pye weed.

Joe Pye weed, Eupatorium fistulosum

Joe Pye weed (Eupatorium fistulosum) is a plant well worth growing, if you don’t already. An excellent back-of-the-border plant that blooms for months from midsummer to mid-autumn, it asks little of the gardener and provides the nectar of choice for bees and butterflies. My clump is about 6 feet tall and thoroughly sturdy, although it would be smaller if I bothered to cut it back in late spring.  Every day I pass it on my way to the mailbox, and every day it is absolutely crawling with bees. And so far, the deer have left it alone.

Gail at Clay and Limestone hosts Wildflower Wednesdays. 

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Mountain mint

I love plant swaps and gardening listservs. It’s so much fun to share plants you need to divide, and to acquire new plants to try.

This week I came into two containers of mountain mint, Pycnanthemum sp. I don’t know what species I have, but I suspect it may be Pycnanthemum muticum, or short-toothed mountain mint. It’s about 3 feet tall, with silvery, slightly serrated leaves an inch to an inch and a half long. Small, buttonlike bracts just above the leaves hold the flowers, which are white, I understand. The plant had finished flowering when I acquired it.  It smells pungently of mint–much stronger than the culinary mint I grow in containers–and is attractive to bees and butterflies. It is actually more closely related to the Monardas than the Menthas, and the resemblance between their respective leaves and bracts is quite plain.

Pycnanthemum muticum heads and bracts

Pycnanthemum muticum heads and bracts (Photo credit: Wikipedia)

The woman who shared it with me warned me that it might be another to keep in a container, because it took over her own backyard (classic behavior of both Menthas and Monardas). Her soil is much nicer than mine, though; fluffy and rich, if the material in the pot is anything to go by. I am wary of the possibility of swapping one assertive species for another, but I planted it in the back of the garden where the heavy rains this year have made the English ivy encroaching from the carrot lady‘s yard go berserk. The soil there is positively unimproved, so if the mountain mint shows signs of thriving, I may dig it up and replant it in a sunken container with the bottom cut out.

Bring on the butterflies and bees!