100 years – 100 Objects: Jamaican Giant Swallowtail

The Houston Museum of Natural Science was founded in 1909 – meaning that the curators of the Houston Museum of Natural Science have been collecting and preserving natural and cultural treasures for a hundred years now. For this yearlong series, our current curators have chosen one hundred exceptional objects from the Museum’s immense storehouse of specimens and artifacts—one for each year of our history. Check back here frequently to learn more about this diverse selection of behind-the-scenes curiosities—we will post the image and description of a new object every few days.

This description is from Nancy, the museum’s director of the Cockrell Butterfly Center and curator of entomology. She’s chosen a selection of objects that represent the rarest and most interesting insects in the Museum’s collections,that we’ll be sharing here – and at 100.hmns.org- throughout the year.

Jamaican Giant Swallowtail – Papilio homerus

Jamaican Giant Swallowtail-4x6This swallowtail species, endemic to the island of Jamaica, is the largest butterfly in the western hemisphere.  Today it occurs only in two small, isolated populations of tropical rainforest and is considered endangered.  We have two males and a female in our collection.

Learn more about moths and their relatives in a visit to the new Brown Hall of Entomology, a part of the Cockrell Butterfly Center– a living, walk-through rainforest at the Houston Museum of Natural Science.

You can see more images of this fascinating artifact – as well as the others we’ve posted so far this year – in the 100 Objects section at 100.hmns.org

Fall Butterflies in Houston

Last week I gave a workshop/lecture at the Houston Arboretum about “Butterflies of Houston.”  I had not chosen the title, and confess I was a little nervous about the emphasis – I can hold my own talking about butterflies in general, and especially about Central American butterflies, but I am not an “expert” on the local species.  Especially not the “LBJs” (little brown jobs; mostly skippers) of the butterfly world!  However, I put together my slides and gathered some field guides and hoped for the best.

It was a fun class.  The participants (regrettably, only about 9 people) were interested, knowledgeable and enthusiastic about their own butterfly gardening and viewing attempts.  We decided to go ahead with the scheduled field trip on Saturday even though the weather prediction was for possible rain.

spicebush swallowtail larvae
Spicebush Swallowtail Caterpillar.

It was overcast but not raining as we gathered in the Arboretum parking lot.  No butterflies were flying, but one of the participants quickly pointed out a smallish camphor tree that had the characteristic rolled leaves housing my favorite caterpillar, the spicebush swallowtail.  These adorable creatures look like toy snakes – they are bright green with large eyespots on their thorax.   A discussion ensued as to why some of the participants had never had spicebush caterpillars on THEIR camphor (or sassafras) trees.  We concluded (or at least I concluded) that the female butterflies really seem to seek out small trees – young saplings, not mature trees.  Perhaps the young trees haven’t yet upped their levels of caterpillar-deterring chemicals, or perhaps their leaves are more tender.  Or perhaps the caterpillars are simply harder to find on larger trees.  And besides, the butterflies really do seem to prefer the hostplant they are named for – spicebush (Lindera benzoin) – but it really doesn’t do all that well in our area.  In any case, I have noticed the same pattern (more caterpillars on small/young plants) in the citrus-feeding giant swallowtail as well.

Not finding much more in the parking lot, we wandered down the Outer Loop trail to the Meadow.  I had hoped to see a few forest butterflies such as tawny, hackberry emperors, red admirals, or even goatweed leafwings, along the Loop Trail, but no such luck.  However, soon after arriving at the Meadow, I was very excited to find caterpillars of the goatweed leafwing on the Texas goatweed (Croton capitatus, aka hogwort or woolly croton) plants growing abundantly along the roadside edge.  Like spicebush caterpillars, these guys hide in rolled up leaves of their hostplant during the day.  However, in contrast to the whimsical spicebush cats, leafwing catepillars are rather drab, greenish with whitish bumps on the body, and a slightly warty, dark head.  And, they spit copious amounts of bright green fluid when you try to unroll them!  I complained to my companions that I had just pulled two large goatweeds out of my garden after waiting all summer for caterpillars!  Perhaps I had given up too soon, or perhaps one needs to be closer to a forest habitat as a source of the egg-laying females.  Who knows? (This could be tested, however, if someone wanted a definitive answer!)

gw leafwing frass chain

But back to the caterpillars:  another cool thing about leafwings is the unique “frass chains” that the caterpillars make when they are very small.  This damage is also characteristic of tropical members of this family, and I have seen it often in the field – often the first clue that a caterpillar is on a given plant.  What IS a frass chain?  First of all, you should know that “frass” is the technical (and very nice, I think) word for “insect pooh.”  The tiny caterpillars eat the tip off a leaf, leaving just the midvein.  They then use their silk (all caterpillars have silk-producing glands in their mouths) to glue tiny pieces of their excrement (frass) to the end of the midvein, elongating it by as much as ½” (it helps to have a hand lens or magnifying loupe to see this).  They also sometimes glue random bits of dead leaf material along the midvein higher up.  Then, during the day, the little caterpillar, which is about the color of a dead leaf bit itself, sits at the end of the frass chain, hidden in plain sight.  So clever!