Monarchs want YOU to plant milkweed: Butterfly-friendly plants for sale at HMNS

The butterflies need your help! With urbanization, and a host of other factors, monarch butterflies are at risk of not finding places to lay their eggs. So why not help while improving the butterfly traffic through your garden with a butterfly-seducing plant from our biannual plant sale?

Milkweed plants in the genus Asclepias are extremely important for butterflies, especially monarchs. While the blooms provide copious amounts of nectar for many different butterflies, the foliage is an essential part of the monarch butterfly’s life cycle. Milkweeds are the only plant monarch caterpillars will eat. In other words, they can’t live without it!

Native milkweed plants grow along roadsides and in open fields. The butterflies find them by honing in on their volatile chemicals and finally locate the exact plant by “tasting” nearby plants with special receptors called chemoreceptors on their feet. Once a gravid female (one who has mated and is ready to lay eggs) finds a good milkweed plant, she will lay eggs on it — and the miraculous process of metamorphosis has begun!

There are about 100 species of Asclepias in the United States, and over 30 in Texas — but monarchs seem to prefer some of them over others. According to a study by Linda S. Rayor, described in The Monarch Butterfly: Biology and Conservation, when given a choice, monarchs prefer to lay eggs on other species of milkweed over the native species Asclepias tuberosa.

Butterfly - Tropical Milkweed

Besides being a host plant for Monarch larvae, Tropical Milkweed (A. curassavica) is a great nectar source for many butterfly species!

Why? Different Asclepias species contain different cardenolide concentrations (cardenolides are the chemicals in the milkweed leaves that taste bitter). As they eat, the caterpillars store these toxic chemicals in their bodies and thus become distasteful to their predators. A. tuberosa has been found to contain low amounts of cardenolides compared to most other species of milkweed. Although it is unclear how monarchs “know” this, they do not usually use A. tuberosa as a host plant.

Several other native milkweed species, however, are great host plants for the monarch. Asclepias asperula (Antelope Horns), A. viridis (Green Milkweed), A. incarnata (Swamp Milkweed) and A. oenotheroides (Zizotes Milkweed) are some of the more commonly found milkweed plants in our area that monarchs use as host plants.

Unfortunately, most of the native milkweeds are hard to find in plant nurseries. One reason is that their seeds require moist stratification to germinate, and even with this pretreatment, germination can be splotchy. Furthermore, young plants of A. asperula, viridis and oenotheroides take several seasons to establish their thick taproots, and can be hard to transplant.

On the bright side, most of the native milkweeds, except for A. incarnata, are drought tolerant and can handle being mowed. Swamp milkweed obviously likes moist soil. All milkweeds grow best in full sun.

Butterfly - Green Milkweed

Asclepias viridis, Green Milkweed

Most gardeners are familiar with tropical milkweed, or Asclepias curassavica. This plant is commonly available in local plant nurseries and attracts butterflies like a magnet! Its bright orange and gold flowers are irresistible to many butterflies, and the high levels of cardenolides in its foliage make it especially sought out by female monarchs looking for a place to lay their eggs. Although it originates in more tropical climes, it is relatively cold hardy and will usually come back from the base of the plant after a freeze. It is also easy to propagate from seed, and in fact will sometimes seed out (make more of itself) in a garden.

So tropical milkweed seems like the ideal plant. However, one issue with this species is that it is not native to our area and does not exhibit the same characteristics of our native milkweeds, all of which die back to the ground in winter. This perennial habit seems advantageous, but it can be a problem for a couple of reasons. Because it has leaves year-round, it may encourage monarchs to overwinter locally instead of migrating to Mexico. It can serve as a host for a disease that affects monarchs, called Ophryocystis elektroscirrha, or simply O.e. This disease is caused by a protozoan parasite and is spread in the dormant stage of its lifecycle as a tiny spore.

These spores are typically on the abdomen of an infected monarch butterfly and can be spread to her eggs or onto the milkweed plants themselves when a female lays eggs. Then, when the caterpillars hatch out of the eggs, they consume the spores that lie on their empty egg shells or on the leaves around the egg and become infected.

Over a few generations, the parasite load can build up to high enough levels that it impacts the butterfly’s survival. Depending on the severity of the infection, the disease can make the caterpillars look a bit grayish and their stripes not as distinct. When the caterpillars pupate, their chrysalis may look brownish or spotted. The butterfly inside may emerge but have problems, such as an enlarged, gray abdomen and weak, faded wings.

Sometimes they emerge and look healthy, but secretly harbor O.e. spores on their abdomens. Other times they don’t emerge from the chrysalis at all, or get stuck while trying to come out.

So what is my point? I thought we were talking about milkweed plants! ;-) The reason this is important is because O.e. spores persist on the leaves of the tropical milkweed plants, waiting for an unsuspecting caterpillar to munch them up. To break this cycle, we recommend cutting your tropical milkweed plants back after a monarch generation has stripped their leaves, especially in the spring and fall. A simple pruning of the plant’s stems about six inches from the ground will get rid of any remaining spores and will sprout new growth in no time.

Some other closely related plants that monarchs will use as a host are Gomphocarpus physocarpus or “family jewels” milkweed, and a species of Funastrum or twinevine. Gomphocarpus is a lot like A. curassavica in that it doesn’t lose its leaves in the winter so it also needs to be cut back periodically to keep it from spreading O.e.

Butterfly - Funastrum cynanchoidies flower

Funastrum cynanchoidies flower

Funastrum or twinevine is an interesting climbing plant native to south Texas and Mexico. The plant is not very impressive looking until the summer, when it puts on beautiful balls of milkweed-like flowers that are great nectar sources for many kinds of butterfly. Another good thing about it is that when monarch caterpillars have stripped all your milkweed plants of their leaves and are still hungry, they will eat the leaves of Funastrum.

With their habitat dwindling due to urbanization, the use of Round Up ready crops, shrinking right-of-ways due to intensive agricultural practices and other factors, monarch butterflies need all the help they can get. The take-home message today is PLANT MORE MILKWEED! (please)

For milkweed and other awesome butterfly host and nectar plants, come visit us at our biannual Spring Plant Sale on Saturday, April 5th from 9 a.m. until we sell out! We are located on the 7th level of the Museum parking garage. Parking is free if you spend $30 or more!

Come early, the plants go fast!

Tagging Monarchs at HMNS

Today Soni (CBC horticulturist) came down to my office and said “You should see all the monarchs in the outdoor butterfly garden. They must be part of the fall migration. Why don’t we tag them?”’

Surely by now most people are aware of the amazing migration undertaken each year by the fall generation of monarch butterflies. As the temperatures cool and the days shorten, monarchs emerging from their chrysalids are cued to head south. Somehow they “know” that their survival depends on it. Before winter sets in, millions of individuals – basically the entire eastern population – start to fly southwest, towards the remote mountain sites in central Mexico where they will spend the winter hanging on the branches of fir and pine trees.

Soni and net
Soni netting butterflies

The spring and summer generations behave very differently. After emerging from its chrysalis, one of the first things a new butterfly typically does is look for a mate (“nature abhors a virgin” as my friend Phil DeVries would say). Mated females search for milkweed plants on which to deposit their eggs; males look for more females! These fair-weather generations probably live for a month or so as adults. The autumn generation, however, does not mate, but saves its energy for the long journey ahead. As fall approaches, butterflies stock up on nectar, packing on fat for the flight and for several months of hibernation.

At the northern edge of the population (southern Ontario/northern Great Lakes area), the migration starts in late August, with butterflies flying on average about 50 miles a day and picking up more migrants as they travel south. By early to mid October, monarchs are streaming through Texas. Virtually the entire eastern population passes through our state – but most of the migrating butterflies pass to the west of us, through Dallas and Austin and San Antonio, then over to Del Rio and into Mexico. Since fewer butterflies typically pass this way, the coastal migration route is not as well known. All the more reason for us to get out there and tag!

monarch tag
How to tag a monarch

Monarch researchers began tagging monarchs back in the early 70s, even before anyone knew where the migrating monarchs were ending up (the roost locations were discovered in 1975). Tagging data collected over the years has enabled us to map the distribution of the population, and to understand that a single generation makes the long trip south and then heads north again after spending the winter, largely dormant, in Mexico. This is hard for some people to understand, especially given that most butterflies only live for a few weeks. The migrating/hibernating monarchs may live as long as eight or nine months.

tag instructions
Tagging instructions from Monarch Watch

The monarchs’ arrival at the overwintering grounds typically coincides with Dia de los Muertos (November 1, Day of the Dead), an important fall festival in Mexico. Some locals apparently see the orange and black visitors as the spirits of their dear departed relatives, returning to celebrate the day. This is not as far-fetched as it may seem; throughout history humans have used butterflies as symbols of the soul and/or reincarnation. Did you know that the word “pysche” in ancient Greek meant both “butterfly” and “soul”?

But back to the present, and Houston. It was a beautiful afternoon so we all trooped outside, armed with nets, pens, data sheets, and numbered tags purchased in advance from Monarch Watch, a non-profit organization based at the University of Kansas that coordinates monitoring efforts. Soni also took a roll of scotch tape and some microscope slides. She is checking the butterflies for OE (short for Ophryocystis elektroscirrha), a sporozoan parasite. If present, the parasite spores can be seen under a compound microscope (they are much smaller than butterfly scales). If there are enough of them in a caterpillar’s body, these parasites can spell death for the butterfly. Luckily, parasite loads are typically low in migrating individuals – perhaps butterflies weakened by the parasites simply can’t make the long journey.

OEtest
Taking scale sample for OE test

Lots of monarchs were coming around the corner of the Butterfly Center, dipping down to our outdoor butterfly garden and stopping to sip nectar from the blooms (they especially seemed to like wheat celosia and purple porter weed). Then they’d head off towards the Sam Houston statue and on in the direction of Rice University (southwest of us!). We caught 11 butterflies in the garden (and missed many more), tagged them (noting whether male or female), took a scale sample, and released them. Off they flew!

We’ll send in our data to Monarch Watch, and of course we hope that someone will find one or more of our tagged butterflies on the roost in Mexico. It is highly unlikely – given the millions of monarchs at the roost – but tagged butterflies (usually dead ones) do get found and reported. If one of ours is found, Monarch Watch will contact us – and they/we will know that butterflies do migrate to Mexico from our area.

tag team
Tag team

Local butterfly gardeners know that a number of monarchs stay in Houston over the winter. We often don’t have killing freezes here, and the recent craze in butterfly gardening means that there is lots of Mexican Milkweed aka Butterfly Weed around.  This plant, Asclepias curassavica, is a perennial from Central America; unlike our native milkweeds, it does not die back in the winter months. Also, predatory wasps, which take many caterpillars during the summer, are mostly gone – so if it doesn’t get too cold, Houston is a good place for monarchs to spend the winter. However, these butterflies are taking the risk of dying should we have a strong cold snap as we did last year.

Here are two great websites with information about these amazing butterflies and about how to get involved monitoring their migration: Monarch Watch at www.monarchwatch.org and Journey North at www.learner.org/jnorth/.

Spring Plant Sale!! This Saturday, 4/9

The Cockrell Butterfly Center is having its Spring Plant Sale Saturday, April 9, 2011, from 9 a.m. to 1 p.m. on the 7th level of the parking garage at the Houston Museum of Natural Science.

Make sure to get there early as plants do sell out! This post is by Soni, one of our Butterfly Center horticulturalists.

HMNS Fall Plant Sale
See more photos from the Spring Plant Sale on Flickr.

We have nectar plants and host plants to attract butterflies to your garden. This year, we have been working on propagating more native plants. This includes:

Black-eyed Susan (Rudbeckia hirta)
Giant Coneflower (Rudbeckia maxima)
Mexican Blanket (Gaillardia pulchella)
American Basket Flower (Centaurea Americana
Creeping Spot Flower (Acmella oppositifolia)
Maypop Passion Vine (Passiflora incarnata)
And others!

Tithonia
See more photos from the Spring Plant Sale on Flickr.

Some of you are probably seasoned butterfly gardeners, but some may be asking yourselves:

How do you garden for butterflies?

The answer is really simple. There are two types of plants that you need to have for a successful butterfly garden: nectar and host plants. Nectar plants have blooms that produce a sugary liquid that butterflies need to consume in order to survive. Some examples of these plants are Porter Weed, Echinacea (Purple Cone Flower), Zinnias, Rudbeckia (Brown and Black-eyed Susans), Monarda (Bee Balm), Lantana, Salvias, Eupatorium (Mistflower), Cuphea, Buddleia, and Tithonia (Mexican Sunflower) among many others.

Gaillardia
See more photos from the Spring Plant Sale on Flickr.

The other type of plants that you need are host plants. Some examples of these are: Asclepias (Milkweed), Passionvine, Citrus, Rue, Fennel, Aristolochia (Pipevine), and Cassias. These are plants that the female butterflies lay eggs on. Certain species of butterflies will only lay their eggs on specific plants such as the Monarch, which only lays eggs on Milkweed. If you see caterpillars on these plants, that is a good thing! Those caterpillars are baby butterflies! The host plant is their food source, which means that the caterpillar eats the leaves. If you want a garden to attract butterflies, but don’t want insects eating away at the foliage, just use nectar plants.

Create a Local Butterfly Habitat!

A lot of these plants are native to Texas and the good thing about this sale is that the Cockrell Butterfly Center specifically chooses plants that will attract the native butterflies and will perform well in the Houston area. If you are not sure what to do or have any questions about gardening for butterflies, our experts will be at the sale to answer them. Come early, the plants go fast!

Butterfly Gardener Alert!

Today’s post was written by Soni, horticulturalist for our Butterfly Center. She and the other employees are hard at word preparing for our upcoming Plant Sale on April 10.

She Was Completely Transparent With Me
Creative Commons License photo credit: Randy Son Of Robert

Got butterflies? Probably not, if your garden suffered freeze damage over the past few months. After this unusually long and cold winter, many of us have lost plants, especially species that are more tropical and not adapted to freezing temperatures.

But now that winter is finally behind us, it’s time to replant! Butterfly gardeners won’t want to miss the Cockrell Butterfly Center’s Spring Plant Sale. It’s happening soon:  Saturday, April 10, 2010 from 9 a.m. to 1 p.m., on the 7th level of the parking garage at the Houston Museum of Natural Science.

Some of you may be seasoned butterfly gardeners, but others may be asking, “How DO you ‘garden’ for butterflies?” It’s quite simple.   For a successful butterfly garden you need two types of plant:  nectar and host plants.

Mix of flowers

Coneflowers and Rudbeckias
Creative Commons License photo credit: Per Ola Wiberg ~ Powi

Thanks to their specialized mouthparts – a long, thin, straw-like proboscis – adult butterflies can only consume liquid food.  The blooms of nectar plants produce a sugary liquid (nectar) that butterflies sip to give them the energy to fly, mate, and produce eggs.  Most nectar plants have colorful flowers borne in showy clusters.  Some examples of good nectar plants for our area are Porter Weed, Echinacea (Purple Cone Flower), Zinnias, Rudbeckia (Brown and Black-eyed Susans), Monarda (Bee Balm), Lantana, Salvias, Eupatorium (Mistflower), Cuphea, Buddleia (Butterfly Bush), and Tithonia (Mexican Sunflower), among many others.

Green Papilio polyxenes caterpillar

Eastern Black
Swallowtail Caterpillar
Creative Commons License photo credit: cyanocorax

In contrast to the adults, baby butterflies, aka caterpillars, have chewing mouthparts and eat leaves.  Many butterflies are quite choosy in their caterpillar stage, and can only survive and grow on specific plants, which we call host plants.  For example, Monarch caterpillars will only eat Asclepias (Milkweed); they cannot and will not eat anything else.  Female butterflies seek out the appropriate host plants for their babies when they are laying eggs.  Some host plants that can be included in your butterfly garden are Asclepias (for Monarchs and Queen Butterflies); Passionvines (for Gulf Fritillaries and if you’re lucky, Zebra Longwings); Citrus and Rue (for Giant Swallowtails); Dill, Parsley, and Fennel (for Black Swallowtails); Aristolochia aka Pipevine (for Pipevine and Polydamas Swallowtails); and Cassia aka Senna (for Sulphur Butterflies).  If you see caterpillars eating these plants, rejoice!  You will soon have lots of beautiful butterflies coming to your nectar plants.

Some of you may think you don’t want caterpillars eating away in your garden.  If so, you can avoid host plants and include only nectar plants.  However, you’ll get more butterflies if you plant both.  We predict that soon you’ll be treasuring every caterpillar!

Many of the nectar and host plants listed above will be available at our sale.  We strive to provide butterfly-attracting plants that are either native or naturalized in Texas, and that perform well in the Houston area.  Our sale is also a good place to learn more about butterfly gardening.  Several experts will be on hand to answer questions and to help you choose plants.


Plant Sale! At the Cockrell Butterfly Center from HMNS on Vimeo.

So save the date:  Saturday, April 10, from 9 a.m. to 1 p.m.  Come early, the plants go fast!