Members of the arachnid class—think spiders, scorpions and harvestmen (daddy long legs)—are often the targets of revulsion, disgust and fear. Yet, they are crucial for ecosystems to thrive. Given the crash in worldwide biodiversity, including what some call the "insect apocalypse," a pair of ecologists at the University of Massachusetts Amherst decided to check in on the general state of insects and arachnids in the U.S.—only to discover massive gaps in the data.