Insect Hike

9 August 2014 Ashland Nature Center, Hockessin, DE

9 a.m. Sunny, 71 F

We started our morning insect walk in the auditorium at Ashland for an overview of collection methods, which was helpful for me since I had missed the lecture. From the first, it was useful information, as we learned that the mesh nets and the canvas nets we use with groups are not just a matter of preference but are designed for different jobs, which should have been obvious, in retrospect, but had not occurred to me. (Mesh nets are aerial nets, for catching insects in flight or when they have landed on top of vegetation. The canvas nets are used for sweeping through grasses and other vegetation, the way I am most accustomed to collecting at Ashland.)

The other methods we learned were interesting but not immediately applicable, pit traps and funnels, lights for collecting insects at night. With the overview done, the group grabbed aerial nets and jars and headed outside. The plan for the morning was to walk through four different habitats, starting with the gardens around the nature center.

Tiger swallowtail

Peck's skipper

The phlox at the beginning of the native pollinator garden was alive with butterflies, tiger swallowtails (Papilio glaucus), black swallowtails (Papilio polyxenes) and Peck’s skippers (Polites peckius).

Starting our walk at 9:30 or so, it was a little early in the day for insects, which become more active as things dry out, but summer is peak season. I expect swallowtails are familiar to most people in Delaware - they are large and relatively easy to see. Once they were pointed out to me, I saw the Peck’s skippers everywhere in the garden too, but they are smaller insects that seem to only open their wings to fly, making them harder to observe. While the swallowtails were all concentrated on the phlox, the skippers were throughout the garden, visiting different plants.

The black swallowtails are actually attracted to plants in the carrot family, Apiaceae, which produce chemicals, psoralens, that makes the plants unpalatable to most insects. The swallowtails are resistant to the psoralens, and eating the plants as larvae allows them to become bad-tasting to birds that would prey on the caterpillars. Some plants in the apiaceae family may reduce the swallowtails’ growth and fertility, but the trade-off appears to work for the insects. Adult swallowtails are palatable, but the insects mimic pipevine swallowtails, which are not.

In addition to seeing the butterflies immediately on starting the walk, we also heard cicadas above. People often think the cicadas only emerge above-ground every 17 years, but that is just the best-known species of the family. The annual or dog-day cicadas (Tibicen canicularis) also spend most of their lives underground, four years feeding on tree roots, but some of the insects emerge every year. As we moved from the gardens to the marsh, we found two cicada exuviae, shed skins, on a basswood tree. These are fun to find, because they continue to cling to vegetation after being shed, and Jim White, who was also our leader for this trip, made good use of the first one we found, attaching it to the shoulder of the boy who joins us for these field studies.

The basswood tree turned out to be a treasure trove of insects, and with more than a dozen people examining the leaves and branches, we found many insects, eggs and signs quickly. The tree attracted our attention because the leaves showed obvious signs of being fed on by insects, and as we explored it, we found eggs of a true bug, homoptera; leaf miners, which are leaf hoppers related to cicadas; the first of many tussock moth caterpillars we would see throughout the day and in nearly every habitat; and an assassin bug nymph that was decorated with the white substance produced by wooly aphids it had eaten. The wooly aphid sign was also present on many of the leaves, and even more of the plants closer to the ground along the trail.

As we had in the garden, we found Japanese beetles (Popillia japonica) very prevalent alongside the marsh, with one group covering leaves of plants that were also popular with daddy long-legs. These familiar bugs are also misunderstood - while they aren’t insects, they aren’t spiders either. Daddy long-legs are a different kind of arachnid known as harvestmen, distinguished from spiders by having just one body segment rather than two. (Insects have three.)

Once on the boardwalk in the marsh and standing among the tall grass and other plants that are doing so well during the summer, we started to find different insects. There were several kinds of dragonflies and damselflies, including a widow skimmer (Libellula luctuosa) that Jim caught so we could have a closer look. We saw a field cricket, a colorful true bug, a plant beetle, and ants protecting aphids, which they will essentially farm as a food supply, an incredible bit of behavior that provides one of those rare examples of similarity between us and insects. But I was surprised not once but twice by a find that is relatively common, even in my city yard - a praying mantis.

The praying mantis is a cool insect and one most everyone is familiar with. Large, sleek, predatory insects, their unique head shape and the easily visible weaponry on their forelegs make them exciting to see. Austin caught one and was keeping it on his hands while waiting for the group to make its way back and mentioned that they are an alien species, originally from China. As a child, I had been told not to mess with a praying mantis because they were a protected species, so this surprised me. (It turns out praying mantis is not a protected species in the United States - this is apparently a common urban myth. They can also deliver a painful bite, I am told, although this one just kept trying to walk up his arm and away.) When the rest of the group made its way back, though, Jim said this one may have been a Carolina praying mantis (Stagmomantis carolina), a native mantid. The primary difference between the two is that the Carolina praying mantis is smaller than the Chinese praying mantis (Tenodera aridigolia), making them very hard to differentiate, because a small animal could either be the native or a young alien.

From the marsh we crossed Barley Mill Road to hike up into the sugar bush trail woods, finding a few insects in the managed woodland meadow before reaching the hill. There was the comma butterfly (Polygonia comma), which used to be called a hop merchant but shows a white comma on the underside of its wing, making its new name apt. A related butterfly has more of a question mark on its wing. We also saw a blue-tip damselfly, a red admiral butterfly and a robber fly - a predator that catches insects on the wing with its legs.

 

Examples of different tussock moth caterpillars found during the day

Just as we started up the trail into the woods, we found another tussock caterpillar - it was interesting to see the minor variations from caterpillar to caterpillar, showcasing the diversity of species, or possibly even of individuals. Once in the woods, we split off into pairs to see what we could collect. In the area we explored, Jessica and I found many leaves that were glued to one another, but could not locate the insect responsible, so we took an example of the joined leaves to share with the group. 

Ground beetle larvae

Under a log, a prime site for finding insects, as well as various other animals, we turned up a small green caterpillar and a couple of insects under a film that had been spread across an opening in the wood. I cleared part of the film for a better look at the insect that had first gotten my attention, and a second moved under the film, so I stopped disturbing it, opting instead to bring the whole log to the group. This guaranteed we caught everyone’s attention and led to our discovery being looked at early on. The film was apparently produced by the insects themselves, which were ground beetle larvae (from the Carabidae family).

The leaf mystery was solved for us by another group, who found the insect responsible, the leaftier. (I noticed during the day that most of the insect names seem fairly kind, stating facts about the animals that could be their most identifiable trait, unlike a few of the birds we came across earlier this year, whose names were not only unrelated but actually misleading.) The leaftier is a caterpillar, but the one the group found will never have the chance to metamorphose. 

Parasitized leaftier caterpillar

It had been parasitized by a wasp, bee or fly. In the photo you can see a small white protuberance sticking out of the side of the caterpillar; that is the parasitic insect, which hatches inside the caterpillar, feeds on it and then emerges. The eggs of the parasite are introduced various ways. Some wasps lay the eggs in the caterpillar. Some flies attach eggs to the outside of the caterpillar, and when the larvae hatch, they burrow into it. And others lay eggs on the plants that the caterpillars eat. This particular example of nature’s incredible diversity is especially stomach-turning, I have to admit, but not uncommon.

Other insects found in the forest included ants, millipedes, beetles, a lightning bug (a kind of beetle), and termites, which provided a nice opportunity for a naturalist party trick. The ink in some ballpoint pens, especially those made by Bic, apparently, has a chemical in it that mimics termite pheromones. Jason drew a circle in his field notebook and placed the termite on it, and the insect followed the line around the page for a time, before it seemed to decide that path wasn’t working and started exploring on its own. Before leaving the forest clearing, Jim pointed out the stone lice on the large piece of gneiss we often have kids sit on for photos - if you look closely, the surface of the rock seems to move because of the many small insects on it.

As we left the woods, we paused over the stream to look for a tiger spiketail dragonfly, which can only be found flying up and down spring-fed creeks about two feet over the water. It was a bit late in the season to find one - they are more commonly seen in July - but Jim knew one patrolled the area of the creek by the bridge, so we waited for a few minutes to see if it would turn up. It never did, but the still, quiet attention to a small bit of the world was valuable in itself. Even on these field trips, on which every person is interested in learning more about the natural world, it can sometimes be easy to move quickly, to focus on the goal, to fail to appreciate the larger picture. Ironic, perhaps, but logical too, as we’re trying to learn about specific plants and animals each time. I guess it speaks to the task of fully understanding our place in the world being made up of multiple tasks - learning who we share the land, water and sky with; spending the time without an objective to learn without seeking; trying to consider a place at large as well as all the individuals who make it up.

Our last habitat for the day was what has become a riotous goldenrod meadow just off the parking lot as Ashland, with vegetation grown up to my shoulder and higher. We again split up into pairs to see what we could find, noticing a gall on the goldenrod early on. A couple sweeps through the goldenrod didn’t turn up much, although that was more evidence of bad luck or technique than a true indication of what was around. When we got to a stand of joe pye weed, easily seven feet tall, we had a bit more luck. There were a number of metallic sweat bees crawling over the flowers, halictids that were small, relatively calm and beautiful.

Beauty moth larva

The joe pye weed also yielded a beautiful collection of silver eggs in a narrow oval on a leaf and an orange and blue plant hopper that would not cooperate for a photo but was a large and beautiful example of the group. We gathered up again to share what we had found. Someone produced a beauty moth larva, which mimics bird droppings as protection, and others shared finding red aphids on the goldenrod and an ichneumon wasp on the joe pye weed. 

Ichneumon wasp

The wasp was an impressive sight, with its long antennae, nonexistent waist and long abdomen. We caught another related one after the trip wrapped up, a different species. The wasp group came up in the woods as well and was initially most memorable for the difficulty it was giving everyone in spelling it.

Jim emptied a collection of vegetation onto a canvas net held taut to see what we could find picking through it, and the technique caught a number of insects, from a harlequin bug nymph to various shield bugs, both adults and nymphs. The one that got Jim’s attention, though, was a homopteran, a plant hopper, that had a protuberance on its head that looked like a horn and was a less common find than most of what we had been seeing all day. There was a crab spider and grasshopper nymphs, a small milkweed beetle and a small wasp.

In just over a couple hours of walking a relatively small bit of land around Ashland, we discovered a diverse collection of insects and evidence of others. Insects are animals we are accustomed to ignoring, at best, or seeking to exterminate in more antagonistic settings, and it was fun to seek them out. They provided one more route into the beauty and diversity of the natural world, especially as I sought to take better pictures, close-ups and examples of the insects in habitats. Exploring the places they lived and the ways they fashioned homes for themselves, like the carabid beetle larvae under the log, provided a larger perspective on these small creatures and the efforts they make in life that are familiar to us as well. And it also provided an unexpected bit of camaraderie, as more than one of us on the hike reminisced about checking out insects as children, sometimes to the detriment of our social status.

This year common animals, familiar locations and personal ignorance have all impressed me with how much we stand to gain by slowing down and paying attention to the world around us, and our insect field trip was another great example of the benefits we can enjoy by doing so. Just under a nearby leaf or hidden next to a stalk of grass, there are complex and beautiful creatures leading lives completely unknown to us, though not unrelated. Especially with a camera, the insect walk turned out to be just as much fun as birding or any other nature hike, and it’s perhaps even more accessible.