Big-eyed bugs (Geocoris spp. Fallén, Hemiptera: Lygaeidae) are ubiquitous, omnivorous insect predators whose plant feeding behavior raises the question of whether they benefit or harm plants. However, several studies have investigated both the potential of Geocoris spp. to serve as biological control agents in agriculture and their importance as agents of plant indirect defense in nature. These studies have demonstrated that Geocoris spp. effectively reduce herbivore populations and increase plant yield. Previous work has also indicated that Geocoris spp. respond to visual and olfactory cues when foraging and choosing their prey and that associative learning of prey and plant cues informs their foraging strategies. For these reasons, Geocoris spp. have become models for the study of tritrophic plant-herbivore-predator interactions. Here, we present detailed images and ecological observations of G. pallens St？l and G. punctipes (Say) native to the Great Basin Desert of southwestern Utah, including observations of their life histories and color morphs, dynamics of their predatory feeding behavior and prey choice over space and time, and novel aspects of Geocoris spp.’s relationships to their host plants. These observations open up new areas to be explored regarding the behavior of Geocoris spp. and their interactions with plant and herbivore populations. 1. Introduction Geocoris spp. Fallén (Hemiptera: Lygaeidae), commonly known as big-eyed bugs, are generalist insect omnivores which occur naturally worldwide [1]. Geocoris spp. are well known to prey on a variety of insects, including several economically important agricultural pests [1, 2] but have also been reported to feed on plant material [1–6], particularly seeds [1, 5, 7]. Several studies in laboratories [1, 4, 6, 8–14], agricultural fields [1, 8, 15–21], and natural habitats [22–31] have investigated the potential of multiple Geocoris spp.—including G. bullatus (Say) [1], G. ochropterus (Fieber) [10], G. pallens St？l [1, 20–22, 24, 26–31], G. proteus Distant [32], G. punctipes (Say) [4, 6, 9, 11–18, 20, 21, 33], G. uliginosus (Say) [16, 19, 33], and G. varius (Uhler) [32]—to serve as biological control agents to protect plants against herbivores. These studies have found that individual Geocoris spp. accept a variety of insect prey, and the field studies have also shown that Geocoris spp. reduce herbivore populations [1, 15, 17, 18, 20–24, 26–29] (but see [25]) and increase plant yield [23, 31]. Thus, despite plant feeding, the net effect of Geocoris spp.-plant interactions is usually beneficial
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