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Previous studies concluded that species in the coccinellid genus Stethorus Weise, although obligate predators of tetranychid mites, exhibit a strong numerical response only to high population densities of their prey. The study reported here was conducted to test the hypothesis that in western Washington red raspberries, Stethorus punctum picipes Casey is capable of detecting and attacking spider mite populations of very low density which are distributed in small, widely scattered patches during the early part of the growing season. In addition to using conventional leaf sampling methods, S. p. picipes interactions with prey were examined by observing their response to prey patches introduced into the field from laboratory cultures. Our results indicate that S. p. picipes is active at low prey densities, although undetected by conventional sampling methods, and is capable of locating rare, small prey patches. This finding suggests that dispersal and searching ability, rather than numerical response are the key components of this preypredator association. KEY WORDS Stethorus punctum picipes, spider mites, raspberry PREVIOUS STUDIES OF Stethorus Weise spp, con

The hobo spider, Tegenaria agrestis (Walckenaer), and the related Tegenaria duellica Simon are very similar European spiders that have become well established in the northwestern United States and British Columbia. The hobo spider is considered to be medically important; T. duellica is considered harmless but is often misidentified as the hobo spider. The current distribution of the hobo spider includes southern British Columbia, Washington, Oregon, Idaho, northern Utah, the western half of Montana, western Wyoming, and two small, isolated populations in Colorado. T. duellica is found mostly west of the Cascade and Coastal mountain ranges from southern British Columbia to central Oregon. In large human population centers where both species are sympatric, T. duellica is usually more common than the hobo spider. Data from a total of 1,232 hobo spiders and 395 T. duellica are included in this study.