The most significant predictors of bug biodiversity in Los Angeles are proximity to the mountains and temperature stability throughout the year, according to a study we co-authored with Brian V. Brown of the Natural History Museum of Los Angeles County and colleagues at the University of Southern California and California State University.
The project used data from the museum’s BioSCAN project, where volunteers across Los Angeles allowed insect traps to be installed on their property between 2014 and 2018.
The analysis showed some surprising results. For instance, land values had little impact on the overall diversity of arthropods, specifically spiders and insects. This finding challenges the “luxury hypothesis,” the notion that wealthier neighborhoods, which tend to have more trees, always have greater biodiversity — an assumption that generally holds true for birds and mammals, including bats.
The BioSCAN study identified over 400 different species of bugs across Greater Los Angeles, many surviving despite pavement and habitat loss.
In fact, urban environments can be attractive to some invasive arthropod species. Often called urban opportunists, such species frequently come in waves that replace or restrict current species. For instance, about 20 years ago, Los Angeles’ native black widow spiders (Latrodectus hesperus) began to be replaced by brown widow spiders (Latrodectus geometricus). Recent evidence shows these interlopers are now being replaced by noble false widow spiders (Steatoda nobilis).