Biological Control
<br>The tachinid flies Triarthria setipennis and Ocytata pallipes are the two main parasitoids of F. auricularia in its native range. T. setipennis is generally the more abundant species, causing significantly higher infection rates. However, O. pallipes sometimes can exert high rates of parasitism;it seems to be better adapted to coastal climates and may in regions with maritime climates be equally suited for the control of F. auricularia (Phillips, 1983;Kuhlmann et al., 2001). Both species have been released repeatedly into the USA, Canada and New Zealand (Atwell, 1927;Davies, 1927;Crumb et al, 1941;Evans, 1952;Kuhlmann et al., 2001). Only T. setipennis is known to have established and spread to large areas of the USA and Canada (Dimick and Mote, 1934;McLeod, 1954;O’ Hara, 1996;Kuhlmann et al., 2001).<br>An intensive breeding and release program of T. setipennis originating from the Mediterranean region started in 1924 and lasted until the 1930s in Portland, Oregon, where it became well established (Dimick and Mote, 1934;Spencer, 1945). Since then, it has also established in Washington, California, Idaho, Utah, New Hampshire and Massachusetts (O’ Hara, 1996). It was also released in Connecticut and Rhode Island but has not been recovered there (O’ Hara, 1994).<br>In Canada, releases of T. setipennis were made in British Columbia (1934–1939), Ontario (1930–1941) and Newfoundland (1951–1953) using flies originating from Oregon (Getzendaner, 1937;McLeod, 1962). The species established in British Columbia and Newfoundland but did not reach high population densities (Mote, 1931;Dimick and Mote, 1934;Spencer, 1947), possibly due to poor adaptation to local climatic conditions (Kuhlmann et al., 2001). Additional releases of the species collected from climatically better matching sites in Switzerland, Germany and Sweden were made in the 1960s. New introductions into Newfoundland were followed by an average increase in parasitism (Morris, 1971, 1984;Morry et al., 1988), but in Nova Scotia, no establishment of T. setipennis could be confirmed (Kuhlmann et al., 2001). Five additional attempts were made in the 1980s to establish T. setipennis in the Ottawa area but it is not known whether it has established (Kuhlmann et al., 2001). The early studies on the establishment of T. setipennis in Newfoundland indicated a considerable reduction in earwig numbers, which was most probably due to high levels of parasitism in the mid-1970s (Morris, 1984;Kuhlmann et al., 2001). Since 1978, no further evaluation of parasitoid impact has been undertaken (Kuhlmann et al., 2001).<br>During the 1930s, some O. pallipes adults were released but only established temporarily in Oregon (Mote, 1931;Clausen, 1978). Pupariae of this species were also shipped to New Zealand for release there but whether the fly became established is not known (Davies, 1927;Evans, 1952). T. setipennis and O. pallipes have also been assessed for their suitability and safety to control F. auricularia on the Falkland Islands and both species are part of an on-going release programme (Maczey et al., 2016).<br>Details of the biology of T. setipennis and O. pallipes are provided by Thompson (1928), Mote et al. (1931), and Kuhlmann (1994, 1995).<br>Apart from the above-mentioned studies in Newfoundland, little information is available on how much effect these natural enemies have on earwig populations.
Detection
F. auricularia is primarily a nocturnal species, hiding during daytime in dark places, where it tends to aggregate. Its presence in the agricultural environment can easily be established by looking under loose bark, stones, pots, wooden boards etc., or by providing artificial hiding places such as upturned flower pots filled with straw or cardboard. Using corrugated cardboard rolls or bands on trunks of trees or grapevines is an easy way to detect earwigs in orchards and vineyards. They can be easily seen on crop edges and on trees and vines when active and feeding at night (Department of Agriculture and Food, Government of Western Australia, 2015).
Despite the considerable size of last instars and adults detection is difficult in shipments. With vegetables, a sample will need to be cut open in order to reveal any hiding earwigs. Sometimes submergence of fruits and vegetables (e.g. cauliflowers) in cold water will drive earwigs out. Frequently they hide in the cores of apples and pears, in which case their presence can often be detected through frass and some external damage around the remnants of the calyx through which they usually enter the inside..
It is also difficult to detect contamination with earwigs in bulk loads, timber and balled up or potted plants.
