Very Hungry Caterpillars

No, this is not the start of an Eric Carle children’s book. It’s the start of a blog post all about gregarious feeders! Unlike the lone green caterpillar of the book that goes chomping through fruits and cakes and slices of salami, some caterpillars can be seen feeding and living in large groups, and as such are labeled ‘gregarious’. We have found many of these fascinating species on our grounds.

Tussock Moth

Milkweed tussock moths

Milkweed is famously host to monarch caterpillars, but many other species depend on it as well. The tussock moth caterpillar is a crazy-haired and charismatic species that seems to appear out of nowhere and turn your milkweed plants into skeletons, eating an entire plant in a matter of days!

Euchaetes egle are orange, white and black, reminding me of my grandmother’s calico shag carpet from the ’70s. As nostalgic as that may be, don’t touch! Their hairs are urticating, meaning they break off into skin and cause irritation. The Latin buffs might remember that “urtica” translates to “nettle”. It is best to let them devour the plants and go on their merry way.

What about the monarchs? Will there by any milkweed left for them? The solution is always to plant more! Try several different species of milkweed to diversify your selection and increase the available habitat.

Walnut Moth Caterpillar

Just last week I noticed a black caterpillar with wispy white hairs crawling along the sidewalk near our greenhouse. Just as I stooped to get a closer look, I saw another. And another. They were everywhere! Crawling every direction on the sidewalk, in the grass, over the rocks and up the side of the building. I followed them back to their host tree, a young walnut. These were walnut moth caterpillars, Datana intergerrimma. There I found a wiggling mass of hairy caterpillars on the trunk. They hatch on the leaves, defoliate the tree with their voracious appetites, then travel down the trunk to disperse and find a bit of open soil to dig in and pupate.

Checkerspot Butterfly

In early June we get lots of calls asking “what is feeding on my Echinacea and sunflowers, and how do I kill it?”. It is usually checkerspot butterfly larvae. These small black caterpillars are lined with tufts of black hair, and they can turn leaves to lace right before your eyes! They host on plants in the Asteraceae family, and their favorites seem to be annual sunflowers and Echinacea purpurea. Through all the years we have had major populations feeding here at the Arb, our Echinacea flowers are doing just fine with no pesticide treatment. They look a little rough for a time, but recover quickly and pop up healthy and green the next spring.

Next time you see a mass of caterpillars feeding on your trees or flowers, don’t reach for the bug spray! Use a tool like the Seek app, or BugGuide.net to properly identify them. If they are native, let them continue to eat and fulfill their ecological role!

Remember, native host plants and native insects have been evolving together for thousands of years. They battle, and sometimes even benefit each other in ways we are still studying today.

Defining Common Horticultural Terms, Part 2

We encounter many enthusiastic new gardeners at FloraKansas who have heard about the importance of planting native plants, but don’t yet have the knowledge base needed to establish a successful planting. If you’re dreaming of a flourishing prairie pollinator garden, let me unpack the why behind the what of a few more horticultural terms for you.

Host Plants

Often, the focus for our gardens is on blooms and succession of blooms, more so than host plants.  Beautiful gardens in full bloom are what we see in catalogs, magazine and books. It is natural to gravitate toward these flourishing gardens that nectar-seeking butterflies need to sustain themselves. However, host plants (food for butterfly caterpillars) will keep them coming back to your landscape for years to come.    

It’s important to plan for the entire life cycle of a pollinator. Butterflies need places to lay their eggs.  Think of host plants as the baby nurseries of the garden. Female butterflies will flit and flutter through your garden looking for the right plant to lay their eggs. Some will lay their eggs on stems, or on the underside of leaves, hidden from predators. If you have a variety of host plants, you will attract a variety of butterflies. 

Newly hatched monarch caterpillar on common milkweed (Photo by Brad Guhr)

Ultimately, the goal of any habitat garden is to provide everything those butterfly species need to complete their life cycle. Food for all stages of their life cycle, protection, and water are needed at different times throughout the year. The tiny larvae (caterpillars) will emerge and begin eating on the host plant. As they eat, they grow until they leave the plant and form a chrysalis. It is a fascinating process that you can watch unfold in your own garden. 

Here are a few host plants and the pollinator they attract:

  • Wild Lupine – Karner Blue butterfly
  • Golden alexander – Black Swallowtail butterfly
  • New Jersey Tea – Spring Azure butterfly
  • Columbine – Columbine Duskywing
  • Smooth Blue Aster – Crescent Butterflies
  • Little Bluestem – Leonard’s Skipper
  • Prairie Violet – Fritillary Butterflies
  • Pearly Everlasting – American Lady
  • Milkweeds – Monarchs
  • Paw Paw – Zebra Swallowtail butterfly
Zebra Swallowtail Butterfly on Pawpaw tree at the Arboretum, photo by Janelle Flory Schrock

Resource: Holm, Heather. Pollinators of Native Plants: Attract, Observe, and Identify Pollinators and Beneficial Insects with Native Plants. Pollination Press, 2014.

Sunlight Defined

Knowing how much light you have within your landscape is an important piece to a sound design. By simply watching sun patterns throughout the year, you will be able to determine how much sunlight your garden receives. Industry standards and labeling can then be used to assist in selecting the right plants for your landscape conditions. Here are some terms worth knowing since all plants require sunlight to grow, but differ in the amount and intensity of light needed to prosper. 

  • Full sun – Plants need at least 6 hours of direct sun daily
  • Part sun – Plants thrive with between 3 and 6 hours of direct sun per day
  • Part shade – Plants require between 3 and 6 hours of sun per day, but need protection from intense mid-day sun
  • Full shade – Plants require less than 3 hours of direct sun per day

Full Sun

Not surprisingly, this type of light describes what most prairie plants need. They enjoy open, bright sunny locations with direct sunlight for most of the day. This could also be morning shade/afternoon sun or vice versa, as long as there is at least 6 hours of continuous sunlight. Most of these plants have deeper root systems or adaptations that help them endure this light intensity for the growing season. 

Let experience be your guide when situating plants. Yes, some plants can handle full sun, but need protection for the hot afternoon sun. Or they can handle full sun with consistent moisture. This is the other reason to understand your site, including soil moisture, soil type, root competition and drainage.  All these factors directly affect plants too.  

Sun loving prairie plants

Part Sun and Part Shade

These light definitions are quite a bit different than plants for full sun.  Plants for part sun and part shade obviously require less light, more importantly, the light intensity is a key factor for their endurance and success.  Filtered sun for most of the day or morning sun afternoon shade fit the bill for situating plants.  Too much direct sunlight for too long a period will stunt plants needing part sun or part shade. 

There is often a fine line between getting too much sun that the plants suffer and getting too little light that the plants don’t bloom. For either group, providing direct morning sun is often the best choice.

Full Shade

Most shade plants require anything from the dappled shade found under deciduous trees, indirect light found on the north side of the house or deeper shade found under evergreens. In our area, growing shade plants can be a challenge because we are trying to grow shade plants in what was once a prairie environment with intense full sun. True shade plants often perish because they get too much sun, too much hot dry wind and/or too little moisture.

To successfully grow shade plants in our area, they need protection and consistent moisture. Any shade gardens must mimic the woodland environment. Loamy soils with leaf litter, consistent moisture – but not too much! – and protection from drying winds. It can be a challenge, but shade gardens can be carefully created with the proper light conditions, too.

Dyck Arboretum woodland garden with columbine, woodland phlox, white woodland aster and solomon’s seal

Discovering Host Plants

My phone is chock full of caterpillar photos. It seems I am constantly stooping down to examine another caterpillar, and to document what it is eating. I am a big fan of all insects, but especially these charismatic transformers. With their plump bodies and endless colors, it is not hard to see why people are becoming more interested in attracting them to the garden.

Viceroy caterpillars can be hard to spot. They disguise themselves as bird poo to appear less appetizing, and it works!
This one was spotted just off the sidewalk at the Arb eating willow leaves.

Host plants are a key part of that process. Caterpillars of all kinds often have a specific food plant or plant family that they need to survive. While I am familiar with monarchs on milkweed and swallowtails on parsley, there is a whole world of interesting host plants out there to utilize in the landscape.

Potluck

My house cats can be picky eaters, but caterpillars are even worse. Many of these little creatures can only feed on a handful of plant species. Their mothers may have to fly miles and miles to find the right plant to lay her eggs on. That is why it is so important to support the native insects of your area by gardening with the native plants they have evolved with for millennia.

Recently I added a few new host plants to my mental list of must-haves for caterpillar habitat.

  • Aspens and willows for viceroy butterflies
  • Primrose and lythrum for sphinx moths
  • Baptisia for broom moths
  • Sumac for spotted datanas
A group of white-lined sphinx moths devoured a primrose patch. They also like to chow down on winged lythrum (Lythrum alatum), a great native plant for wet areas.
Genista broom moth caterpillars (Uresiphita reversalis) are a cheery shade of yellow. They love Baptisia and can make the plants look quite ragged. But, by the time these caterpillars are feeding heavily in midsummer, the Baptisia has already bloomed and is done for the season anyway.
These spotted datana (Datana perspicua) caterpillars are gregarious feeders, meaning you usually find them in groups with their siblings. They munched away on this aromatic sumac (Rhus aromatica) for a few days, and tripled in size!

Appreciate, Don’t Hate

As my knowledge of host plants grows, so does my appreciation for native plants and the intricate ecosystem they support. I am so encouraged to hear more people calling them friends rather than foes, and wanting to identify and observe rather than squish and poison. It is always best practice to pause before sprinkling that pesticide – your garden will thank you, since most caterpillars do more good than harm. Changing our perspective about caterpillars, and all insects, is key to maintaining a functional, healthy food web. If you are interested in finding more caterpillars in your Kansas landscape, reach out to the staff at Dyck Arboretum for consultation, follow our Facebook and Instagram accounts for educational content, and mark your calendars for next spring’s FloraKansas fundraiser!

Coneflowers: A Lesson in Host Plants

Coneflowers are so emblematic of the prairie. I love to include these prairie denizens in many of my designs. They are quite adaptable and I love the yellows, purples and pink colors of the true natives as they bloom during the summer.  The new cultivated varieties are attractive too. A mass of coneflowers with little bluestem make a nice combination by providing color and texture through the growing season. But right now, many of the plants are full of little black or brown caterpillars that are using Echinacea and Rudbeckia as their food.

Coneflowers as host plants

We are getting calls from our members and customers, and are seeing damage on our plants as well. Coneflower leaves are blackening, getting holes and disappearing. Contrary to how you may feel, this damage is an indication that your garden is functioning properly. Host plants are the vital food source that caterpillars live on. Adult butterflies will seek out these plants to lay their eggs on because they know that the caterpillar cannot travel far and will not survive if placed on a plant that they cannot eat. These caterpillars will eventually turn into checkerspot butterflies or a relative in that family. 

Think differently about your landscape

One of the goals of any garden – besides beauty – is to have pollinators in your garden. Sometimes they might not immediately be in the form you desire. Sometimes pollinators or their caterpillars may eat your plants or deform them.  Don’t be too hasty to spray or remove the culprits. They are doing what comes naturally to them and it is often better to leave the insect. These insects are fantastic food for fledgling birds as well.

Understand the life cycle

The caterpillars eating your coneflowers will make cocoons in a week or so and then turn into butterflies.  We must learn to embrace these caterpillars and accept some damage. The coneflowers will eventually recover. The tradeoff is that we create habitat suitable for butterflies to complete their life cycle. The “ugly, hairy” caterpillars will morph into beautiful butterflies that are equal to the beauty of the flower. 

The key to a successful butterfly garden is to plant both nectar and host plants, so that the butterflies will have a food source in all stages of their life cycles. We often design our landscapes as nectar sources and forget that these pollinators need host plants too. So as you design your landscape, include flowering plants that produce nectar and also double as host plants.

Other host plants

  • Black Eyed Susan (Rudbeckia hirta) Host plant for: Silvery Checkerspot, Gorgone Checkerspot, Bordered Patch butterfly
  • Aster spp. Host plant for: Pearl crescent, Painted Lady and more
  • Coneflower (Echinacea spp.) Host Plant for: Silvery Checkerspot and more
  • Hollyhock (Alcea spp.) Host plant for: Painted Lady, Common Checkered-Skipper and more
  • Golden Alexander (Zizia aurea) or Dill (Antheum graveolens) Host plant for: Black Swallowtail, Anise Swallowtail and more NOTE: The Black Swallowtail will feed on any plants within the Parsley family.
  • Sunflower (Helianthus spp.) Host plant for: Silvery Checkerspot, Painted Lady and more
  • Milkweeds (Asclepias spp.) Host plant for: Monarch
  • Mallow (Malva spp.) Host plant for: Common Checkered-Skipper, Gray Hairstreak , Painted Lady and more
  • Violet (Viola spp.) Host plant for: Great Spangled Fritillary, Variegated Fritillary, Meadow Fritillary and more

Be A Good Host for Insects

Monarch ovipositing on common milkweed (April 9, 2017).

There are many positive things that can be said about insects. They are important to healthy ecosystems. If you have any appreciation for wildlife of any kind in Kansas, you have insects to thank. Aside from a handful of pests, they are beneficial to humans as well. Click HERE to see an earlier blog post on why I am in awe of insects.

Many insect species require a specific host plant or group of plants to feed their young. Therefore, it should be no surprise that greater plant diversity leads to greater insect diversity and ultimately a greater abundance of wildlife. I like to see more biological diversity in urban landscapes and this is why my landscaping tendencies trend towards more plant diversity rather than less.

Butterfly enthusiast and master gardener Lenora Larson gave us this similar message during a March 2017 winter lecture. She highlighted more than two dozen species of butterflies and moths that folks can easily attract to their landscape with specific host plants. A summary of her presentation, host plant and butterfly species lists, and helpful references can be found HERE.

Monarch egg on common milkweed (April 10, 2017).

Monarch Update

A little over a week ago on April 9, I saw my first couple of northerly migrating monarchs of the season. There were many other reports of first of season monarchs reported that weekend as well. In the week since, newly emerged milkweed shoots more often than not are found hosting one to six monarch eggs each. Yesterday on April 18, nine days after the first monarch siting, I observed the first two hatched caterpillars. More on the plight of the monarch and why we are so carefully observing this progress can be found HERE in an earlier blog post.

Newly hatched monarch caterpillar on common milkweed (April 18).

We’ll be touting at our spring plant sale the many benefits of gardening with Kansas native plants. Attracting insects and biological diversity to your landscape is one of those many benefits.