After posting the link to the urban wildlife article, I heard about a group of scientists that study true bugs, or insects in the order Hemiptera, in roundabouts in England. I have since been given an article that I thought would be great to share with you all. It is called “Biodiversity on urban roundabouts-Hemiptera, management and the species-area relationship”- you can find it here.
Before I jump into what they found, I wanted to let you know a little bit about what “true” bugs are. Even though the word “bug” is thrown around a lot, to us insect nerds, it actually has a very specific meaning. True “bugs” are insects in the order Hemiptera, which means “half wing” because most true bugs have front wings that are half hardened, like beetles, and half membranous, like flies. True bugs have straw-like mouth parts, sort of like a butterfly and fly but not at all like a tiger beetle’s mandibles. True bugs also have old school insect growth: instead of pupating (larva/caterpillar into a cocoon), they just hatch and grow slowly, like us humans, and you will often find adults and young, known as nymphs, together. Aphids are true bugs, so are assassin bugs, so are box elder bugs and cicadas and stink bugs! Cool stuff. I’d say they are my favorite after beetles :).
The study of true bugs in the city looked at the diversity of Hemipterans in roundabouts of difference sizes and under different management. Roundabouts, for those of you unfamiliar with them (i.e. US peeps), are those circular islands in the middle of an intersection of two or more roads- check out the link above for a cool wiki-animation of how they work. The Roundabouts used in the study were green roundabouts, or covered in vegetation, that were either mowed frequently, infrequently, or not at all and subject to herbicide treatments or not. They surveyed the true bugs in the grass by vacuum sampling- yes, there are bug vacuums out there for easy sampling- and in the trees by beating branches and catching what fell. The scientists then compared numbers and types of true bug species between sites.
They found that the larger the roundabout, the more tree species present and that leads to more species of true bugs! Not too surprising, but they did also show that the arboreal, or tree-living, true bugs tended to be associated with one type of host tree, indicating that high tree biodiversity in a roundabout can lead to increases in true bug biodiversity, even in a small cemented-in urban circle of vegetation. The grass-living true bugs did not necessarily increase with higher grass species, but instead responded to the management of grassy roundabouts. In particular, they found that roundabouts that were mowed very infrequently- like once a year- had many more true bug species.
Why does less mowing mean more true bugs? Well, when areas are mowed less, the grasses and flowers have time to establish and grow, making grasslands with plants of various sizes and structures- exactly what true bugs need to mate, lay their eggs, and eat. This study is exactly the type of research that we need in order to understand what bugs need in order to thrive in the city. It shows us that if we truly want more urban biodiversity, we have to learn how to both choose and manage the correct species to plant and introduce into our urban greenways in order to attract and maintain more species.
As this study shows, with a few more tree species and less mowing, we can create a rambunctious garden that supports True biodiversity in the city.