It is often desirable to quantify earthworm number or biomass in a given habitat and/or seek to collect them. A few species show their presence by surface casting (e.g., Aporrectodea longa) or creation of middens (e.g., Lumbricus terrestris) but most require some form of intervention to locate them, due to their totally subterranean existence. To this end, various techniques have been developed to enable earthworm collection. Digging is the simplest, as it requires only a spade and perhaps a quadrat for density calculations but may detect only near surface (epigeic) earthworms and horizontal burrowing (endogeic) species. Adults of deeper burrowing (anecic) species may be missed unless the researcher is prepared to dig a hole to a depth of several metres