Caterpillar Mania – Part II

Posted on August 29, 2018 by Katie Schmidt

Part II of my blog series about caterpillars will cover their bodies and behaviors, and the habitats you can build for them at home.

Anatomy

Once you look closely, you can easily see that caterpillars are more than just a pudgy worm. They often have visible faces, charismatic coloration and interesting behaviors. Caterpillars are actually six legged creatures (because, of course, they are insects!), though it looks like they have many more. The six real legs are located at the front of the body near the head. All other legs are considered ‘prolegs’; appendages for gripping, and moving, but not true jointed legs.

Some caterpillars seem to have horns or antennas visible on their heads, but you are actually seeing tentacles. Most caterpillar antennae are very small and inconspicuous, located near the mouth, while tentacles are large, fleshy and can occur in several places along the top of the body. Tentacles on the head help them sense the world around them while tubercules (fleshy knobs along the body) are usually for intimidating predators.

You may have questioned at one time or another how caterpillars ‘breathe’, or if they do at all! In fact, insects breathe through holes in their bodies called ‘spiracles’. These tiny openings (found along the sides of most caterpillars) bring air into the trachea of the insects and usually deliver oxygen directly to the body tissues.

A white-lined sphinx moth (Hyles lineata) caterpillar blending in with a rusty brown redbud stem. As long as my finger at least, this is one huge caterpillar!

Dude with a ‘Tude

When you are such a delicious and nutritious snack for birds, it pays to defend yourself and stay hidden! In the last post I discussed defense mechanisms such as special coloration, camouflage or toxic setae (hairs). But sometimes their defenses have much more attitude! For instance, swallowtail caterpillars are famous for their charismatic show of osmetrium, a forked organ that shoots out suddenly to startle predators. When threatened, the caterpillar quickly extends the osmetrium to scare the offending spider, bird, or ant. A great video of this reaction is found here. The organ resembles a snake tongue or tiny horns and can secrete unpleasant odors to further repel a would-be predator.

Monarch caterpillar on a swamp milkweed leaf outside the Arboretum greenhouse.

Flinging Frass

Caterpillars with osmetrium purposely produce unpleasant odors to scare predators, while other butterfly larvae take drastic measures not to produce an odor. Silver-spotted skipper caterpillars are famous for their ability to fling their frass (the fancy word for caterpillar poop) incredible distances. Scientists believe this helps keep predators such as wasps from detecting where the caterpillar is living. To be sure no predator finds their cozy home, a tiny skipper caterpillar can shoot their turds up to 5 feet away! That’s about 30 times their body length. They accomplish this feat through a controlled burst of high blood pressure.

You have to see it to believe it — https://www.youtube.com/watch?v=WW5j7eY15Yw

Silk

Caterpillars have amazing organs called ‘spinnerets’ that produce silk. We know that silkworms are bred especially for their prolific silk production, but many of the caterpillars in your very own backyards also make silk. Some caterpillars use silk to escape predators by attaching it to a leaf and ‘bungee jumping’ to safety. They also use it to make mats or trails around the plant they live on to make travel easier. Some caterpillars will make elaborate tents or ‘bags’ out of silk, with hundreds of their kin inside with them. And when it comes time to mature into a butterfly, a silk ‘button’ helps the chrysalis hang from a leaf or twig. Moths make their entire cocoon out of silk, surrounding themselves in a soft yet protective barrier.

The fall webworm (Hyphantria cunea) is a well known but harmless pest. Characterized by a large sticky silk nest and a voracious appetite, they rarely cause lasting damage to otherwise healthy trees. By Alison Hunter [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)], from Wikimedia Commons

Habitat

Regular visits to the Arboretum will provide ample bug-watching opportunities, and our staff are eager to chat with you. But the best way to learn about insects is to see them in person. Plant a native garden of your own where insects can thrive! Lots of wonderful resources exist about butterfly gardening, but remember: it isn’t a butterfly garden unless it includes host plants. They need host plants (the specific plants the larvae feed on) and native nectar to sustain their entire life cycle. Otherwise, as Lenora Larson might say, you are just “bartending”, serving only “adult beverages” to the butterflies but not supporting the larvae. If you need some inspiration to create your own native garden paradise for butterflies and moths, talk with one of our staff members at the upcoming FloraKansas Native Plant Festival!

Caterpillar Mania – Part I

Posted on August 23, 2018 by Katie Schmidt

This time of year is great for caterpillar hunting. I have been finding lots of amazing, colorful critters munching away on the foliage here at Dyck Arboretum. I am always eager to get a picture of them, if I can, so that I can properly identify them later using guides and help from the internet. In doing so, I become engrossed in their beautiful and strange anatomies – spots, stripes, horns, hairs and amazingly grippy legs. There is much to know and discover!

I get close up photos of insects on my phone using a clip on macro lens. By doing so I can see the tiny details on this white-lined sphinx moth caterpillar (Hyles lineata), like the yellow tips on his legs and the white spots on his head.

Caterpillars vs Worms

When a child sees a caterpillar, they might be tempted to point and say “Oooh, worm!”. But we must remember that caterpillars are not worms, they are larvae. Larvae is the immature form of an insect. A true worm, such as an earthworm, isn’t an immature form of anything. There are several other easy to notice differences:

Worms do not move on legs – Caterpillars do
Worms are not insects, and do not metamorphose into insects – Caterpillars change into an adult butterfly or moth
Worms can be microscopic or gigantic, up to 180 ft long! – Caterpillars are visible, but not larger than 12cm

Also, caterpillars often sport wacky colors and patterns while most of the world’s worms are much more inconspicuous. Earthworms and some marine worms, roundworms, and tapeworms are usually sporting brown or tan skin. However, many types of ocean dwelling flatworms are incredibly colorful, though you won’t likely confuse these guys for caterpillars.

An adult black swallowtail caterpillar feeding on Zizia in our greenhouse. These swallowtails can only feed on plants in the Parsley/Carrot family.

This black swallowtail caterpillar is in one of its early ‘instars’ or phases of development. It will shed its skin as it gets bigger, and coloration changes during this process as well. In the top left, you can see a black swallowtail caterpillar farther along in its development.

Hairy and Scary

Caterpillars are genius defense players. They are so packed full of protein and delicious to predators, they have had to evolve many ways to protect themselves. Some caterpillars, like the monarch butterfly, make themselves taste bad by eating milkweed leaves with toxins in them. Others try to look intimidating with aposematic coloration – body patterns and colors that warn predators to stay back! And some, like the spicebush swallowtail, even grow fake eye spots on their bodies to fool their hunters into thinking they are snakes. My personal favorites are the hairy ones. Caterpillars will sometimes grow hairs to make them hard or unpleasant to swallow. What bird wants a mouth full of hair anyways? Sometimes these hairs are designed to fall off and lodge in the skin/mucus membrane of whatever is disturbing it, causing an itchy rash in some people.

This is a cycnia moth caterpillar feeding on Asclepias sullivantii in our plant nursery. This little guy needs milkweed just as much as the monarchs, but doesn’t get the same press for some reason. I made sure not to touch him because of all those potentially itch-inducing hairs!

In part II of this topic, I will talk a little bit about the specific parts of their body, special caterpillar diets, silk making abilities, and how you can design your very own caterpillar-attracting butterfly garden. Until then, keep a lookout for these special critters and do a little discovering of your own!

Let’s Talk about Mulch

Posted on August 16, 2018 by Scott Vogt

It is no secret that mulch is great for the landscape. There are so many benefits when you add mulch around your plants. Mulch is a great insulator, because it modifies the soil temperature. It reduces erosion, prevent weeds from germinating, retains soil moisture, provides a buffer between equipment and the trunks and stems, and increases the aesthetics of the overall landscape. As you add mulch to your garden, here are some things to know:

How much mulch is enough?

Mulching is not an exact science, but as a general rule, we try to apply 2-3 inches of mulch consistently throughout the landscape. This depth of mulch will control weeds by decreasing sunlight exposure, which prohibits seeds in the soil from to germinating. More than three inches of mulch seals off the soil and suffocates your plants. It is extremely important that the plants are able to get the oxygen they need. Spread the mulch evenly and don’t build a mulch volcano around the base of the tree. Since mulch decomposes slowly, it is good to periodically check the depth and add some as needed.

Mulch volcano at base of tree. A big no no!

Nicely mulched new planting

What is the best way to mulch?

We start by laying out a garden hose, which allows you to visualize the curves and width of a bed. You can either spray the area inside the hose or dig up the vegetation and let it slowly die. When the area is cleaned up, we begin applying the mulch and leveling it to the desired depth. Keep in mind that too much mulch will encourage growth of the roots into the mulch, where it will be susceptible to freeze damage. The ideal 2 to 3 inch depth of mulch will keep the roots in the soil.

When is the best time to mulch?

We are mulching throughout the year, but direct most of our efforts in the spring or fall. As we clean up our display beds in the spring, it is always a good time to freshen up the mulch, too. At this time of year, soil temperatures are beginning to warm and a new layer of mulch will slow down the warming process. A new layer of mulch will also cover seeds that may have landed in the mulch and covering them now will prevent germination. We mulch anytime a new tree or shrub is planted. This practice will keep the soil cooler, help retain moisture longer and insulate new roots from the cold weather. Some thicker mulch areas may benefit from being fluffed from time to time. Simply take a rake and loosen up the top few inches of the mulch.

What type of mulch is best?

We use whatever is available to us. Mulch is not cheap, so we use chippings from the tree trimming service. We have used semi loads of hardwood mulch, which is expensive. It is not as important what you use, but how much you use. Even free mulch can look attractive and function just like the most expensive mulch. For sloped areas, the larger and heavier mulch works the best. It is not as susceptible to runoff or wind displacement. Smaller or finer mulch decomposes quicker too. The bottom line is use what is available to you.

Our mulch pile of chipped up trees

River rock as mulch with blackeyed susan and prairie dropseed

Can I use plants as mulch?

In the book Planting in a Post-Wild World: Designing Plant Communities for Resilient Landscapes, Thomas Rainer and Claudia West develop the ideas of layering plants. There are usually at least three distinct layers of plants: the upper layer filled with taller structural plants used to frame and punctuate the landscape, the middle layer filled with ornamental flowering plants and the ground level that weaves the other layers together and shades the soil, which controls weeds. These layers mimic natural plant communities and each layer is important for the health of the plants. A collection of plants living in community can be extremely drought tolerant and water-thrifty.

Lenora Larson’s Garden with dense plants that smother weeds

A few final thoughts:

Purchase a heavy duty mulching fork and stiff garden rake for leveling.

Essential mulching tools: Silage fork and stiff leaf rake

Insects can be a problem in mulch, so keep it away from the foundation of your house and base of the plants. Termites generally like larger pieces of wood but can even live in the finer mulch, especially if it is too thick.

Landscape fabric under mulch is something we avoid. It only keeps weeds out for the first few years and then the decomposing mulch turns into compost, which is ideal seed bed for weeds. It is also hard to transplant into it and often suffocates the soil. We have purged the Arboretum of just about all landscape fabric. Save your money and buy more plants.

You can use rock as a mulch, but don’t buy the recycled rubber mulch. The rubber mulch may last forever but it does nothing great for the soil or the plants around it. In fact, the compounds and residues that leach over time may do more harm than good.

Happy Mulching!

Cicada Killers

Posted on August 9, 2018 by Brad Guhr

“Hunting, warring, patrolling, tunneling, they do more in two months–the length of their adult lives–than periodical cicadas do in 17 years.” ~Tim Heffernan, The Atlantic

The insect world never ceases to amaze me. I had a new experience with insects in my yard a few evenings ago. A cicada making a ruckus landed on the ground right next to me in my garden. I quickly realized that it was in a tussle with a large wasp. I had heard about cicada killers before, and it didn’t take long to deduce that I was seeing my first one take down its prey. The cicada struggle didn’t last long as the sting and subsequent paralysis happened in seconds. The cicada killer shortly flew and when checking back later, I noticed that the cicada was gone too.

A cicada killer taking down a cicada.

A friend recently posted a great article about cicada killers. Do yourself a favor and read Tim Heffernan’s 2013 brief article on cicada killers in The Atlantic. This article explains the cicada killer’s interesting adult 2-month life, soil-burrowing nest habits, process for taking down cicadas, hatching of their larvae in a cicada’s live but paralyzed state, and the flies that can also parasitize the cicada killers themselves.

Harmless to People

“With bodies up to two inches in length, huge jaws, and glossy black paint jobs streaked with yellow, they are unmistakable, and more than a little intimidating.” ~Tim Heffernan, The Atlantic

Cicada killers are fascinating insects, and you should add them to the list of insects around you that make you say “oooooh”, rather than “ewwwwww!” They may look ominous, but they really are harmless to people.

In addition to taking in the fascinating information in Tim Heffernan’s article, I want you to take away that this insect holds minimal danger for people. Their large size relative to other wasps is due to the fact that they need to wrestle a large cicada to their nest. The warning coloration is probably some form of mimicry that they have evolved to look fearsome like their yellow jacket and hornet relatives. My hope would be that folks could minimize the knee-jerk reaction of reaching for the can of wasp killer whenever they see any wasp, but especially a non-threatening cicada killer. Don’t fall into the societal stigma that causes many people to recoil when they see an insect, and especially a wasp.

The Hymenoptera Order of insects (wasps, bees, and ants) has long been maligned in our society. A quick search for “movies about killer insects” shows that we love to be terrified of insects.

I’d like to encourage a respectful and non-aggressive approach to all insects in general. So, to finish on a calming note, I’ll leave you with an image of a cuddly monarch butterfly caterpillar that I took right outside the Arboretum Visitor Center door this week munching away on common milkweed.

But be careful, it is filled with poisonous cardiac glycosides and if you were only 2 inches tall and you ate it, it could kill you. Aaaaaggghhh!

A deadly monarch caterpillar.

Five Water Saving Practices for your Landscape

Posted on August 1, 2018 by Scott Vogt

Last week the Arboretum staff visited a flower farm near Lawrence. It was interesting to see how they were growing their flowers to be used in arrangements and displays for special occasions. They focused on native plants, but also had some annuals, bulbs and shrubs, too. During our tour, the topic of irrigation and water use were explored, because they are under severe drought conditions. It made me think about our irrigation practices and ways to create a water-wise landscape. Here are five water saving practices for you to implement in your garden.

Choose plants adapted to your site

One of the biggest mistakes I have made when establishing a new garden is choosing plants that I like rather than plants that like the area in which I am trying to establish them. There is a big difference. It is critical to match plants to the site. The closer they are adapted to your landscape the less water they will need to survive. Native plants are always a good choice, because they are already adapted to our climate. Evaluate your landscape’s soil, sun exposure, and moisture content. By understanding these aspects of your landscape, you will be able to make informed plant choices. There is a palette of plants that will almost effortlessly grow in your garden. Grouping plants with similar water needs that match your landscape conditions will ensure success.

Space Plantings Tightly

In their book Planting in a Post-Wild World: Designing Plant Communities for Resilient Landscapes, Thomas Rainer and Claudia West develop the ideas of layering plants. There are usually at least three distinct layers of plants: the upper layer filled with taller structural plants used to frame and punctuate the landscape, the middle layer filled with ornamental flowering plants and the ground level that weaves the other layers together and shades the soil which controls weeds. These layers mimic natural plant communities and each layer is important for the health of the plants. A collection of plants living in community can be extremely drought tolerant and water-thrifty.

Use mulch around trees and shrubs

Mulches can be a blessing and a curse depending your mulching practices. We typically apply a two to three inch layer of mulch around a tree by simply mulching a tree a few inches away from the root flare and extending out to its drip line. Shrubs get the same treatment. It is vital to keep mulch several inches away from the trunk or stem. Please, no mulch volcanoes! Mulches prevent weeds, eliminate erosion, retain soil moisture, help moderate soil temperatures, provide a buffer between equipment and the trunks and stems and increase the aesthetics of the overall landscape. Too much mulch (over four inches) starves roots of oxygen by sealing off the ground suffocating the plants. Old mulch can matte up and restrict water infiltration, too.

Viburnum prunifolium in bloom

Irrigate efficiently

During times of prolonged drought, irrigation may be necessary. Plants naturally go dormant, but in a display bed you can add supplemental water to keep them more vibrant and healthy. We use pressure compensating drip irrigation tubing with emitters spaced 12 inch apart. Drip irrigation puts water where it is needed for optimum efficiency in the root zone rather than on the leaves. If you irrigate with overhead sprinklers, start sprinklers early in the morning or later in the evening. Avoid watering during the hottest part of the day to reduce evaporation and loss from wind. You can also recycle rainfall and create a rain garden.

Pressure compensating 1/2 inch soaker hose

Reduce your lawn

Cool season grass lawns with roots that are maybe six to twelve inches deep are one of the most watered landscape plants. If you think strategically and replace part of a water-guzzling lawn with deep rooted wildflowers, grasses, shrubs and trees or even with native buffalograss, you will save water and increase wildlife diversity in your landscape. You may like open spaces with lawn for play or leisure, but you can scale back the size of your lawn and still have the aesthetics you appreciate. Mow your lawn at the highest height and water only as needed. Turfgrass has its place in the landscape, but maybe not the most prominent place it currently does.

We don’t think often enough about the water we use. It is a precious commodity. Remember the 2011 and 2012 drought in Kansas? We were using tremendous quantities of water to keep our landscapes alive. It made us evaluate each plant according to its response to these extreme conditions. Obviously, some plants did better than others and we lost some plants those years. It made us think critically about our plant choices and irrigation practices. A beautiful and resilient landscape that uses little if any supplemental water is an achievable result. A few changes can make a big difference.