Big-eyed bugs
Big-eyed bugs are small predatory true bugs, 1/8 to 1/4 inch (3–6 mm) long, named for the wide head and large bulging eyes that set them apart from the pests they resemble. Adults and nymphs eat mites, aphids, whiteflies, insect eggs, small caterpillars and chinch bugs, dozens of prey a day. They also suck a little plant sap, pollen and seeds, but rarely cause damage. They are found in lawns and among leaf litter at the base of plants, especially across the southern United States. They were not in commercial production when Cornell's guide was written (2011), and they are sometimes sprayed by mistake because they look like chinch bugs.
At a glance
- Kind
- Wild — conserved, not released
- Adult
- 3–6 mm; broad head, bulging eyes
- Eats
- Dozens of prey a day; 67 prey species recorded
- Egg hatch
- About 1 week
- Nymphs
- 5 instars, 4–6 days each
- Adults live
- About a month
How it works
Big-eyed bugs are true bugs in the genus Geocoris, with about 19 species in North America; G. punctipes and G. pallens are the most common, and G. uliginosus is the species UF/IFAS reports from Florida St. Augustinegrass. Adults and the wingless nymphs both hunt. They take mites, aphids, whiteflies, plant bugs, flea beetles, small caterpillars and many kinds of insect eggs.
Females lay single, sausage-shaped eggs, white to tan with a red spot, on the undersides of leaves and on stems. The eggs hatch in about a week, and the nymphs pass through five instars of four to six days each, so there are several generations a season. They also take pollen, seeds and plant juices; UC IPM calls this harmless and Cornell's guide says it rarely causes economic damage. They are very susceptible to broad-spectrum insecticides.
What it is confused with
The big-eyed bug's problem is that it lives where pests live and looks like several of them. Look at the head: the eyes of a big-eyed bug are large and bulge out to the sides.
- PestChinch bugs — Small, triangular head with small eyes, and white wings with a black spot folded flat over a slender black body; nymphs are red or orange with a white band. Big-eyed bugs are broader-headed, greyer and move with a waggling gait.
- PestFalse chinch bugs — UC IPM lists them as a look-alike. Like chinch bugs, they have smaller eyes, a narrower body and a more pointed head than a big-eyed bug.
- PestLygus bugs (plant bugs) — Also listed by UC IPM as a look-alike: smaller eyes, longer antennae, a narrower head and a distinct triangular plate (scutellum) on the back. They are plant pests, and big-eyed bugs eat their eggs and nymphs.
How to keep it around
Big-eyed bugs turn up on their own in lawns and gardens; keeping them is mostly a matter of not killing them. UC IPM and Cornell suggest:
- Flowering insectary plants that give blossoms throughout the growing season
- Sunflowers as a refuge planting, which Cornell's guide cites as a way to build up big-eyed bug numbers
- Count before spraying and use a threshold, so the lawn is not treated when it does not need it
- No broad-spectrum insecticides; where a treatment is needed, pick a narrow one
Pesticide sensitivity
Cornell's guide calls big-eyed bugs very susceptible to broad-spectrum pesticides, and notes that because they also feed on plants, systemic pesticides may harm them too. Because they are mistaken for chinch bugs, lawns are sometimes sprayed for the predator rather than the pest. Open the compatibility matrix →
When to choose something else
Big-eyed bugs are useful background predators, but you cannot count on ordering them into a lawn. Look elsewhere when:
- A float test finds chinch bugs above threshold in a browning lawn — UF/IFAS reports that predators alone did not significantly cut numbers; see chinch bugs
- Spider mites are building in a greenhouse — buy a predatory mite such as Phytoseiulus persimilis
- Aphids are colonising a crop under glass — use a parasitoid such as Aphidius colemani
Big-eyed bugs by target
What it eats and when it turns up differ by pest. Each page below is the picture for one target.