Hosts or Prey
Predaceous on mites and a wide variety of small insects.
Identification
Bigeyed bug adults and nymphs (immatures) are oval and commonly black, brownish, gray, or reddish. They have a wide head with bulging eyes and prominent antennae. Adults range from about 1/8 to 1/4 inch (3–6 mm) long.
Nymphs commonly resemble the adults in coloration and shape, but are wingless. In older instars the developing wings (wing pads) are oblong and partially cover the abdomen.
Eggs are laid singly on leaves and stems of herbaceous plants. They are oblong and white or pale-colored with a slender projection on one end. Eggs are less than 1/24 inch (1 mm) long and easily overlooked. Shortly before eggs of Geocoris species hatch, the eyes of developing nymphs become apparent as two reddish spots near one end.
Lookalikes
Chinch bugs (Blissidae) and false chinch bugs (Lygaeidae) are plant-feeding true bugs (Heteroptera) that resemble bigeyed bugs. In comparison with bigeyed bugs, chinch bugs and false chinch bugs have smaller eyes, are more narrow (slender) relative to their length, and have a pointed, somewhat-triangular head.
Plant bugs (Miridae) such as the whitemarked fleahopper can resemble bigeyed bugs. Compared with bigeyed bugs, plant bugs such as Lygus species have smaller eyes, longer antennae, and a more narrow head relative to the body width. Adult plant bugs have a distinct triangular area (scutellum) where wings attach to the thorax. In some species the scutellum coloration contrasts distinctly with surrounding tissue as apparent on the western tarnished plant bug, Lygus hesperus. Lygus bugs are pests commonly found on herbaceous garden plants and row crops.
Life Cycle
Bigeyed bugs develop through three life stages. Eggs hatch into nymphs, which develop through five increasingly larger instars. Bigeyed bugs can have several generations per year.
Habitat
Bigeyed bugs are found mostly on low-growing plants, including many field and row crops and in gardens. Adults and nymphs feed by sucking prey's body contents through their needlelike mouthparts. Bigeyed bugs feed on bug nymphs, flea beetles, insect eggs, small caterpillars, and all stages of aphids, mites, and whiteflies. Bigeyed bugs also feed harmlessly on pollen, seeds, and plant juices and are not plant pests.
Bigeyed bugs can provide important biological control of pests in alfalfa, cotton, and certain other crops if conservation (preservation) of natural enemies and compatible integrated pest management (IPM) techniques are employed.
Bigeyed bug abundance can be increased by planting flowering species (insectary plants) that provide blossoms throughout the growing season.
Species
At least six Geocoris species bigeyed bugs occur in California, including Geocoris pallens, G. punctipes, and G. uliginosus. Adults and nymphs of G. punctipes and G. pallens commonly have a brownish to gray body, but coloration varies among individuals. Geocoris punctipes generally are more gray and G. pallens more brownish. Adults of G. uliginosus have a blackish body, as do Isthmocoris slevini and I. tristis bigeyed bugs that also occur in California.
More Information
- Biological Control and Natural Enemies of Invertebrates, UC Integrated Pest Management Program
- Ecological Observations of Native Geocoris pallens and G. punctipes, Psyche: A Journal of Entomology
- Family Geocoridae - Big-eyed Bugs, BugGuide, Iowa State University
- Geocoridae of Mexico, color photos of adults of many U.S. species, Zootaxa journal
- Geocoris spp., Cornell University
- Insectary Plants, UC Integrated Pest Management Program
- Natural Enemies Handbook, UC Integrated Pest Management Program
- Protecting Natural Enemies and Pollinators, UC Integrated Pest Management Program
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Hemiptera
- Suborder: Heteroptera
- Family: Geocoridae
