Wednesday, August 8, 2012


Guest blog post from Merrill Peterson, of Western Washington University and Carol Kaesuk Yoon, science writer for the New York Times, extolling the virtues of moths and the fantastic web resource, Pacific Northwest Moths,

We here in the Pacific Northwest are lucky for many reasons - towering Mount Rainier, schools of delicious salmon, summer harvests of raspberries - and, though not too many people know this, an abundance of beautiful and fascinating moth species. To help people study, better understand and enjoy these species, a group of lepidopterists (people who study butterflies and moths) worked for the last three years to create a new website called Pacific Northwest Moths. So far, there are just over 1,200 species on the site, with ultra high resolution photographs of each one (you can zoom in to see individual wing scales), range maps, detailed species accounts, and even an easy-to-use interactive identification key.

So what's in the region and on our site?

There are moths that hardly seem to be moths at all! Like many other insect species, some species of moths have evolved to look like much tougher, more intimidating and potentially dangerous insects, like wasps or bees. This Hemaris thetis is a bumblebee-mimicking moth that can be found in our region. This chubby clear-winged moth can be found hovering over flowers in broad daylight, sipping nectar. 

Others have evolved to look equally unattractive, but for different reasons - like the species that mimic bird poops, including Tarache knowltoni, which, when it is at rest with only the front wings showing, is easy to mistake for bird droppings.

Some moth species in the region are hard at work, attempting to do what human hands and tools have been unable to accomplish, for example, controlling invasive weeds. The weed known as Tansy Ragwort can be deadly to livestock, and can even harm humans when cattle eat the weed and produce contaminated milk. Tansy Ragwort even produces toxic pollen which can create tainted honey if it's anywhere within two miles of a hive. But this noxious weed is now being challenged by Tyria jacobaeae, a moth species whose caterpillars enjoy munching down this invasive species. 

In addition to having pictures of species of these species and more, the site has maps showing where and when they have been found. In this way, researchers can use the website to track and record any moth species that come within our region, including the odd stray tropical species that wanders up, like this Black Witch Moth. This impressively huge tropical species did exactly that this summer, turning up in July at Priest Lake, Idaho.

Because each species account shows all known sightings of a species, it gives everyone, including scientists, a chance to see how the fauna of our region has changed and continues to change over time. It also allows us to see phenomena such as the massive outbreaks of western tent caterpillar moths, Malacosoma californicum, such as have plagued Island and Whatcom Counties in Washington State this summer.

There are some groups of moths that are interesting, simply for their incredible diversity. For example, one group in our region that is very species-rich, and a real headache for taxonomists, is the genus Euxoa. If you look at the site, you'll find more than 120 species, many of which are extremely difficult to distinguish. 

Moths can also be very important as a food source to bats, birds, spiders, and even foraging bears. Take for example, one of our moth species known as the army cutworm moth or Euxoa auxiliaris. A study in Yellowstone found that grizzly bears eat aggregations of these moths in rock screes, where the bears sit and patiently turn over rock after rock to find the moths hidden on the underside. The moths turn out to be more energy-rich sources of food than blueberries, trout, nuts, or deer meat, and represent 34% of the bears' diet in late summer, when they are fattening up for winter. A single bear can eat up to 40,000 moths per day at their peak!

We envision Pacific Northwest Moths as not only a repository of data already known, but as a place where people can continue to report new sightings, a never-ending citizen science project that can help us understand the ever changing story of the moths of our region.

Tuesday, August 7, 2012


Well, don't we all? By "all," I mean all living things that reproduce sexually. When you think of it mechanistically, an organism's adaptations are primarily directed toward getting its genes into the next generation. Eat, sleep, avoid predators, grow up and reproduce—what else is there? Well, besides keeping in touch through Facebook.

For dragonflies, it's a long larval life in the water, as they eat and try to avoid being eaten. Then the magic of metamorphosis when they leave the water to become an adult winged insect. After that, more feeding and predator avoidance and, most of all, attempting to reproduce.

Male dragonflies spend much of their time at the water. Think of a singles bar, where the males are hanging around in hopes of meeting someone of the opposite sex. That's why those males head for the water. As the larvae are aquatic, the females have to lay their eggs in the water. Because the females have to come to the water to do this, males have a better chance of meeting one there.

Because so many males are at the water, the sex ratio can be extremely skewed there, with dozens to even hundreds of males for every female. Thus for a male there can be extreme competition for mates, and some males never mate in their lifetime. One way to alleviate that is for a male to defend a territory large enough, keeping other males out of his air space, so that he has access to any female that approaches. Many kinds of dragonflies do just this.

When a male damselfly sees a female, he immediately attempts to grab her for mating. He flies up to her, lands on her head and bends his abdomen forward to clasp her "neck" (prothorax) in two pairs of clasping appendages at the end of the abdomen. As soon as he has a good grip, he brings his abdomen forward and transfers sperm from the tip of his abdomen, where they are produced, to a storage chamber called a seminal vesicle in his second segment. From there, the spermatozoa can be transferred to his copulatory organ.

He then signals the female his readiness to mate by swinging her forward. The tip of her abdomen contacts his second segment, and structures on both of them form a firm connection. His genital ligula (penis) then transfers the sperm to the female's vagina, where it is moved to the spermatheca, another storage organ.

They then disconnect from that point, and she is ready to lay eggs. Her eggs travel from her ovary down her oviduct and are fertilized as they pass the spermatheca. She then can insert them into plant tissue with a specialized ovipositor, and the cycle begins again.

Dragonflies do about the same thing as damselflies, but the male fills his seminal vesicle before mating, and he clasps the female's head with three clasping appendages. The majority of dragonflies lay their eggs directly into the water rather than inserting them into plant tissue. See Odonate Oviposition, November 3, 2011, on this blog site.

Dennis Paulson

Nature Blog Network