Friday, January 30, 2015

Spicebush, sulcatone, and mosquitoes

Aedes aegypti, wiki [8]
I fell down the google rabbit hole in a big way earlier today. I was digging around, looking for info on the chemical composition of some of my favorite scents from childhood. I wasn't doing this idly- essential oil companies sell these compounds. My though was this: wouldn't it be nice to blend a fragrance that captures where I grew up? 

Sweetgum Range, from wiki [6]
The aromas of a southern childhood that I settled on were forest soil, cedar, tomato leaves, gardenia, maple syrup, wet dog, and the fragrant terpenes from sweet gum (Liquidambar styraciflua) and spicebush (Lindera benzoin). Most of these were pretty easy to find. Oakmoss and vetiver conjure a forest floor, two varieties of cedarwood oil are manufactured in Texas alone, a tomato leaf accord is a popular perfume top note, blended jasmine and honey smells similar to gardenia, immortelle flower smells of maple syrup, costus of wet dog, etc etc. In fact, the resin of sweet gum’s Chinese cousin, also in the family Liquidambar, is a perfume staple. It is sometimes referred to as a variety of ‘styrax’.

Spicebush was the only fragrance without an obvious analog. Its crushed leaves smell of fresh citrus and camphoraceous cloves (like a hot toddy!). This lovely odor is referenced in its species epithet- ‘benzoin’. Derived from the the resin of trees in the genus Styrax, benzoin is another staple in perfumery. It smells of vanilla, warm powder, and musk. Spicebush was used by early American colonists as a substitute for allspice, and native peoples used it as a panacea, marinade, and fragrant tea. The spicebush swallowtail relies on spicebush as its only larval food source. It is also a preferred food of the gorgeous promethea silkmoths, and its bright red berries are a treat for the birds. 

Sunday, January 25, 2015

A day-flying hypocala moth

The beautiful Hypocala andremona
As far as lepidoptera go, moths came first.  Butterflies are essentially a type of moth, a moth with brilliant colors that flies in the daytime. Moths show up in the fossil record 190 million years ago.  Butterflies appear as a sub group later, perhaps as late as 130 million years ago.  It could be for this reason that there are ten times as many species of moths as there are butterflies. Some of the most primitive micromoths (Micropopterigidae- mandibulate archaic moths) hardly resemble their larger cousins at all. Their caterpillars are slug-like detritivores, and the adults retain their chewing mandibles. They are closely related to caddis flies.

Sphinx moth
 I find moths fascinating because they surround us, but their nocturnal habits assure that we rarely notice them unless they are knocking against our porch lights. There are exceptions, however. Some moths, like the sphinx moths, fly in the daytime. Others, like the Hypocala andremona pictured above, stay up past their bedtime.

I was delighted to find a hypocala moth in south Texas (November 2014). S/he had obligingly posed on an orange bank of flowers, accentuating the bright underwing coloration. They can be a defoliating pest on persimmon leaves as caterpillars, but I can't begrudge them that. It is rare for a tree to die from periodic defoliation. Hypocala moths themselves are heavily parasitized by beneficial insects, especially the trichogramma wasps. To me, they don't seem like a pest that requires active intervention. Supposedly they are most frequently seen in Texas, and they can be found from Central America up through the southern states.

Distinguishing the very similar underwing moths (catocala) from the hypocala moths is not easy. Both are medium-large moths with drab upper wings and colorful, patterned underwings. I read that catocala means "beautiful below" in latin on, so hypocala must mean "beautiful underneath". Basically the same thing. They are both in the Erebidae family, but the precise taxonomic split varies by source.  I doubt I could have teased apart this taxonomic distinction without help from the "Mothing and Moth Watching" Facebook group. Following this group is addictive. People post pictures from all over the world-- who knew there were so many gorgeous moths in China and Brazil?

If I've piqued your interest, you can read more about moths on this blog here and here, or you can become a member of "Mothing and Moth Watching" on Facebook.

Possibly a day-flying large lace border moth (Scopula limboundata)

Monday, January 19, 2015

A visit to the coastal prairie

Gayfeather on the dunes
I spent the end of last week down in San Marcos giving a "Monarchs 101" talk to agency personnel. My monarch talk was something of an opportunistic afterthought, appended to an existing gathering of the Gulf Coast Prairie Landscape Conservation Cooperative (GCP LCC). This organization was formed as a collaborative effort, driven by the Department of the Interior, to protect the Gulf Coast Prairie from threats including climate change and urbanization. Because Texas' geographic extent encompasses the funnel through which the majority of migratory monarchs pass every spring and fall, and because the Feds have been under a lot of pressure to develop a strategy to save the monarch butterfly migration, the GCP LCC and their partners are tackling this issue. I was brought in to provide an overview of monarch biology. I've discussed monarchs and other milkweed butterflies before in this blog.

It's easy to forget about the coastal prairies up here in the Great Plains. After living in Nebraska, it's a stretch to imagine a tall grass prairie within earshot of the surf, but I've seen it. Last November I stopped off in Corpus Christi to visit Padre Island on my way to the Texas Butterfly Festival. There I found tall grass species commingling with yucca and hardy halophytes.

As the southern-most extension of the tall grass prairie, you recognize seemingly misplaced familiar plants. I noticed little bluestem and gayfeather, among others. You also get coastal species, like sea oats and fleshy succulent forbs. It sure felt tropical-- my leeward arm was entirely coated in mosquitoes. Luckily, I was wearing a thick wool sweater over a flannel shirt. All I could think was "malaria, yellow fever". Prior to eradication efforts, visiting coastal Texas must have been a real gamble. I spent a summer as a research assistant in the salt marshes of coastal Virginia, but I've never seen mosquitoes like that.

A tallgrass dune system
The gulf coast prairies are also unusual because they exist in a land that receives more than enough rain to support forests and other vegetation. You can find these prairies from Lafayette, Louisiana to south Texas. Supposedly, edaphic (soil) characteristics and fire maintained these grasslands' open canopy.  I would guess that salinity in the water table also prevents trees from getting established.

crested caracara
Corpus Christi is far enough south that you get some semi-tropical birds. In fact, Padre Island is renowned for birding. The National Park Service website claims that Corpus Christi won the "birdiest city" award for 10 consecutive years. You get both winter residents and migrants. It is one of the richest areas for birding in North America. Obsessive birders travel from all over to get 'lifers'.

I didn't do much birding, but I saw a pair of crested caracaras gliding and diving in the dunes. These funky raptors are most closely related to falcons, but they live like vultures. They are inefficient hunters, and prefer carrion and thievery to catching their own dinner. They also look like they are wearing poorly fitted toupees. This 'bad wig' effect, combined with their pink faces, make them look rather non-threatening for a bird of prey. Their range barely extends into the US. The crested caracara heartland is Central America and northern South America.

This bird doesn't mind the seaweed
Another distinctive facet of the Gulf Coast Prairies is their exposure to the by-products of petroleum exploitation. When I asked native Texans about the beaches, their responses tended towards "Eh." A friend of mine reminisced about digging tar balls on the beach as a child. Additionally, something about the rotation of the Gulf Coast gyre leads to heavy trash and seaweed accumulation. The Padre Island entry booth had signs posting the tides, the flag warning, and the levels of trash and debris on the beach.  It's a shame, but the birds still come. If you want to add to your life list, or see a unique prairie system, it's still worth a trip.

Pelican and cormorants hanging out in the surf

Thursday, January 8, 2015

Action plants!

Longleaf pine savannah, Louisiana
It is an interesting time to love rare and unusual plants. Just a few months ago, a man in Boone, NC became the first to be charged with a felony for poaching the rare (and highly lucrative) ginseng. Dried ginseng is worth four times its weight in silver. Most growers keep their operations secret because poaching, not the vagaries of weather, pests, or animals, is the biggest threat to their livelihoods.

A venus flytrap in situ at the Green Swamp
Again in North Carolina, a few days ago four men were the first to be charged with felonies for poaching venus flytraps. Unbelievably, before the law was changed December 1st of last year, the maximum penalty was a misdemeanor and a $50 fine. $50 seems down right paltry when you consider that venus flytraps are only found on poor soils in the longleaf pine savannah on the coastal plain of North and South Carolina. The Nature Conservancy estimates that there are fewer than 35,000 venus flytraps remaining in the wild.

I have lived most of my life in the southeastern United States, and I have had the privilege of seeing many different types of carnivorous plant in the wild in North Carolina, Alabama, and Louisiana. Plants develop carnivory as a means to get more nutrients on poor soils. Simply put, this strategy doesn't pay on better ground. Snap traps, sticky trap, or pitcher, these plants all must expend energy to build these contraptions. While flytraps are rather limited in distribution, sundews and pitcher plants can be found along much of the Atlantic coast and in the Great Lake states.

A sundew (no, that isn't my hand and no, I didn't pick it)
classic pitcher plant
I have seen venus flytraps, sundews, and pitcher plants. These three families, along with bladderworts, make up some of the major clusters in carnivorous plant taxonomy.  Sundews and flytraps are actually somewhat related. Flytraps seem to have evolved from a sundew-like ancestor.

Sundews capture their prey with a sticky trap mechanism- what looks like dew is actually an adhesive. Once an insect is caught it will not be released. The venus flytrap, cousin to the sundew, is instead reminiscent of a steel trap. Once an insect brushes its trigger hairs, the jaws snap shut and imprison it.

Pitcher plants are less closely related, and their traps are much more passive. An insect falls in and is slowly dissolved in an enzyme bath at the bottom of the pitcher. Should it try to climb out, downward facing hairs trip it up and hinder its escape.

Another type of pitcher plant. Notice the hair.
Texas has one species of pitcher plant (Sarracenia alata) and up to four species of sundew (Drosera brevifolia, D. capillaris, D. intermedia, and D. tracyi).  I haven't yet found these plants, but the BONAP maps show them pretty far inland. Sundews are unobtrusive and hard to spot, but pitcher plants might be worth an expedition. Especially during their summer bloom.

A blooming pitcher plant

Longleaf pine savannah, North Carolina