- Fostering Insect-Human Relationships through Design
The ecological world is dense with invisible connections, a web of interspecific interactions barely comprehensible to humankind. We don't always have the time for slow and careful observation, nor do we have many of the physiological tools to witness these relationships. When we walk in a forest, we are oblivious to the mating pheromones released by moths or the electric fields around flowers that can be sensed by bees. To reveal these relationships is to open a window into a surreal and magical world. I had one of these experiences while watching a Zoom lecture by Dr. Doug Tallamy just before the start of the COVID-19 pandemic. He described host plant relationships—the dependence of a specific insect, often a butterfly or moth species, on specific species or groups of plants during their larval stage as caterpillars.
In the abstract, this recalled my understanding of commonly celebrated inter-species relationships like monarch butterflies and their need for milkweed to survive. But Dr. Tallamy's work expanded upon these relationships as more than a singular anecdote: he suggested they were fundamental to the entire food webs that define native landscapes and ecosystems. Without the presence of certain plants, you don't support (or see) certain insects. You're unlikely to find larval fritillaries in a landscape without violets, or zebra swallowtails larvae in landscapes without pawpaws. You'd be hard pressed to find larval cecropia moths without birches, cherries, or maples—and even less likely to find larval viceroy butterflies without willows.
While inter-species relationships are not always as singular and rigid as the milkweed-monarch relationship, the complicated web of life is made slightly clearer through understanding these dependencies.
These relationships became personal when I reflected on early years chasing yellow and black swallowtail butterflies around my family's porch in suburban Delaware. On a whim, I looked up their host plants and was stunned—respectively, the butterflies depended on tulip tree and spicebush, the predominant tree and understory shrub in the fragment of deciduous forest around my childhood home. Exploring this forest fringe was what inspired me to become a landscape architect, but I never understood the fundamental connection between the plants and the insects that surrounded me. Suddenly, my work in landscape architecture—developing design strategies, site proposals, and planting plans—took on new meaning. In addition to designing for aesthetics, for sustainability, and for maintenance, should we also be designing for insects?
But why support insects at all? There are quite a lot of insects out there. Over 10 quintillion individual insects live alongside us at any given moment (Smithsonian 2022). They have the largest biomass of any terrestrial animal group and are the class with the most species diversity (Smithsonian 2022). As E.O. Wilson said, it's a "primarily invertebrate world" (Wilson 1987, 344). Many insects function as threats or nuisances to human society—including mosquitoes that spread viruses, termites that destroy structures, and locust swarms that devastate crops. Despite their threats, we just don't know that much about insects—and because of their diversity and sheer abundance, it's likely that there are millions of insect species yet to be described (Smithsonian 2022).
While it's easy to be dismissive of these small creatures, insects are critical to human life. The ecosystem services they provide are vast. They are a primary food source for wildlife, they control pests, pollinate most of the world's plants including many of our crops, are a food source for humans, decompose waste, and build soil food webs. Many entomologists reference E.O. Wilson to illustrate this concept. At the opening of the National Zoological Park in 1987, he described a world without insects and other invertebrates: "If humans were to disappear tomorrow, the world would go on with little change. But if invertebrates were to disappear, I doubt the human species could last more than a few months (…) Within a few decades, the world would return to the state of a billion years ago, composed primarily of bacteria, algae and a few other very simple multicellular plants" (Wilson 1987, 345).
Wilson's words become very...