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Individual study: Excluding European earwigs Forficula auricularia from artificial nesting sites increases nesting activity by native bees in Cosumnes River Preserve, California, USA

Published source details

Barthell J.F., Gordon W.F. & Thorp R.W. (1998) Invader effects in a community of cavity nesting Megachilid bees (Hymenoptera: Megachildae). Environmental Entomology, 27, 240-247


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Exclude introduced European earwigs from nest sites Bee Conservation

Thirty drilled pine wood solitary bee nest boxes were suspended from 15 valley oak trees Quercus lobata on the Cosumnes River Preserve, near Sacramento, Caifornia, USA, in 1990 (Barthell et al. 1998). The boxes each had twelve 10 cm-deep holes, 0.65 cm in diameter. Boxes were placed in pairs. One on each tree excluded crawling earwigs Forficula auricularia using the sticky barrier Tanglefoot. The treatment substantially reduced the number of earwigs found in the boxes and allowed a greater total number of bee cells (during the peak bee nesting week, there were 134 cells in boxes with Tanglefoot, 45 cells in untreated boxes). The majority of nesting bees in this study were native species of the leafcutter bee genera Megachile and Osmia although introduced species of Megachile were also present.