The Making of a Kill Jar

I often hear stories from plant lovers about their initial nonchalance concerning plants. The common refrain seems to be that they were fascinated by wildlife and largely ignored plant life until they came to the realization that plants were integral in the lives of animals and play a major role in shaping the environments that support all life. Such an epiphany spawns an insatiable obsession with botany, at least for some people.

I seem to be on the opposite trajectory. It’s not like I have ever really been disinterested in animals; I’ve just been significantly more interested in plants and haven’t bothered to learn much about the animal kingdom (with the exception of entomology). My growing fascination with pollination biology (see last year’s Year of Pollination series) isn’t much of a stretch because insects have always appealed to me, and their intimate interactions with plants are hard to ignore. Ultimately, it is my interest in urban ecology and wildlife friendly gardening that is driving me to learn more about animals.

I started this year off by finally reading Doug Tallamy’s popular book, Bringing Nature Home. Tallamy wrote a lot about birds in his book, which got me thinking more about them. I then discovered Welcome to Subirdia, a book by John Marzluff that explores the diversity of birds that live among us in our urban environments. I then found myself paying more attention to birds. Many bird species rely on insects for food at some point in their lives. Plants regularly interact with insects both in defending themselves against herbivory and in attracting insects to assist in pollination. It’s all connected, and it seems I wouldn’t be much of a botanist then if I didn’t also learn about all of the players involved in these complex interactions.

So, now I’m a birdwatcher and an insect collector. Or at least I’m learning to be. Insects are hard to learn much about without capturing them. They often move quickly, making them hard to identify, or they go completely unnoticed because they are tiny and so well hidden or camouflaged. With the help of a net and a kill jar, you can get a closer look. This not only allows you to determine the species of insects that surround you, but it can also help give you an idea of their relative abundances, their life cycles, where they live and what they feed on, etc.

insect net 2_bw

As the name implies, if you’re using a kill jar, your actions will result in the death of insects. Some people will be more pleased about this than others. If killing insects bothers you, don’t worry, insect populations are typically abundant enough that a few individuals sacrificed for science will not hurt the population in a serious way.

Kill jars can be purchased or they can be made very simply with a few easy to find materials. Start with a glass jar with a metal lid. Mix up a small amount of plaster of paris. Pour the wet plaster in the jar, filling it to about one inch. Allow the plaster to dry completely. This process can be sped up by placing the jar in an oven set on warm. When the plaster is dry, “charge” the jar by soaking the plaster with either ethyl acetate, nail polish remover, or rubbing alcohol. I use nail polish remover because it is cheap and easily accessible. It doesn’t work as quickly as pure ethyl acetate, but it is less toxic. Place a paper towel or something soft and dry in the jar. This keeps the insects from getting beaten up too much as they thrash about. Once the insect is dead, it can be easily observed with a hand lens or a dissecting microscope. It can also be pinned, labeled, and added to a collection.

There are several resources online that describe the process of collecting and preserving insects, including instructions for making an inexpensive kill jar, which is why I am keeping this brief and will instead refer you to a couple of such sites. Like this one from Purdue University’s extension program. It’s directed toward youth, but it includes great information for beginners of any age. This post by Dragonfly Woman is a great tutorial for making a kill jar, and there are several other posts on her blog that are very informative for insect collectors of all experience levels.

I guess you could consider this part of my journey of becoming a naturalist. Perhaps you are on a similar journey. If so, share your thoughts and experiences in the comment section below.

How Pitcher Plants Eat Bugs (Frog Optional)

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A few months ago at work I captured this photo of a frog inside of a pitcher plant. Do you see it? It is pretty well camouflaged and poking its head out just enough to intercept curious insects lured in by the promise of nectar, eating them before they can make their way into the tube. Either way, approaching insects are about to meet their fate. Whether by plant or by frog, they are destined to be consumed lest they turn away in time.

This frog was hiding inside the modified leaf of a species of Sarracenia, a carnivorous plant commonly known as a North American pitcher plant. There are at least eight species of Sarracenia, all of which naturally occur in the southeastern region of the United States. One species, Sarracenia purpurea, also occurs in the northeast, the upper Midwest, and throughout much of Canada. Sarracenia is in the family Sarraceniaceae along with two other genera of pitcher plants, Darlingtonia (the cobra plant, native to northern California and southern Oregon) and Heliamphora (the sun pitchers, native to South America). Plants in this family are not to be confused with the distantly related tropical pitcher plants which are in the genus Nepenthes (family Nepentheaceae).

The natural habitats of Sarracenia are sunny, open areas that remain permanently wet, including meadows, savannahs, fens, and swamps. The soils are acidic, nutrient poor, and typically composed of sandy peat commonly derived from sphagnum moss. In the southeast, less than 5% of the original (pre-European settlement) Sarracenia habitat remains, threatening its survival in the wild. Sarracenia oreophila (green pitcher plant) is currently listed as critically endangered on the IUCN Red List.

Flowering occurs in the spring, usually before pitchers form. Individual flowers are formed on tall stalks that rise straight up and then bend at the very top, hanging the flower upside down. Early flowering and tall flower stalks help prevent pollinating insects from being consumed by the plant. In his book The Savage Garden, Peter D’Amato describes the flowers as “showy, brilliant, and very unusual – a wonderful bonus to an already handsome class of foliage plants.” The flowers are either yellow or a shade of red and last about two weeks, after which the petals drop and a seed pod forms. Seeds are released from the fruits in the fall.

Flower of Sarracenia rubra (sweet pitcherplant) - photo credit: www.eol.org

Flower of Sarracenia rubra (sweet pitcher plant) – photo credit: www.eol.org

D’Amato writes that Sarracenia are among the “most ravenous” plants, with each leaf having the potential of trapping “thousands of nasty insects.” In some cases pitchers even flop over, heavy with the weight of bugs inside them. The specifics of capturing and killing insects varies between species of Sarracenia, but in general prey is lured to the opening of the pitcher with a combination of nectar, scent, and color. Upon entering the tube, gravity, waxy surfaces, drugs, and hairs force the captives downward where they are eventually consumed by enzymes and microbes. Digested insects provide the plant with nutrients necessary for growth – nutrients that otherwise are taken up by the roots of plants that occur in more nutrient rich soils.

Sarracenia purpurea (purple pitcher plant) is unique in that its pitchers lack a “hood” or “lid” – a standard feature of other species of Sarracenia that helps keep rain from entering the pitchers. Instead, the pitchers fill with water and insects are killed by drowning. The most brutal killer is probably Sarracenia psittacina (parrot pitcher plant) which has an additional opening inside of its pitcher. The opening is small and difficult to find again once an insect is on the wrong side of it. The inside walls of the pitcher are covered in long, sharp, downward pointing hairs, and the struggling insect is pierced repeatedly by the hairs as it makes its way to the bottom of the tube to be digested.

Hoodless pitchers of Sarracenia purpurea (photo credit: www.eol.org)

Hoodless pitchers of Sarracenia purpurea (photo credit: www.eol.org)

Hooded pitchers of Sarracenia leucophylla (photo credit: www.eol.org)

Hooded pitchers of Sarracenia leucophylla (photo credit: www.eol.org)

According to D’Amato, “the Sarracenia are one of the simplest carnivorous plants to grow, and certainly among the most fun and rewarding.” Learn more about growing North American pitcher plants by consulting D’Amato’s book and/or by visiting the website of the International Carnivorous Plant Society.

Want to learn more about Sarracenia? The Plants are Cool, Too! web series has a great video about them:

Other carnivorous plant posts: