Dicyphus hesperus

How it works

Adults and nymphs feed on prey, using water drawn from the plant to digest it. Whitefly eggs and larvae come first, both greenhouse and tobacco (sweetpotato) whitefly, and a female can eat about 24 young greenhouse whitefly nymphs a day. When whitefly is scarce it turns to spider mites, moth eggs, and thrips and leafminer larvae. In greenhouse trials run by Koppert researchers in 2018, it established on tomato and suppressed potato psyllid as well as whitefly. It has been tested in British Columbia tomato houses since the late 1990s and is now used in greenhouse tomato in Canada, the northern US and Mexico.

Females lay their eggs inside plant tissue, so the first generation is invisible. On moth eggs at 75 °F (24 °C) nymphs took about 18 days to reach adulthood, and about 29 days on cattail pollen alone. Females can live seven weeks on tomato when they have animal food. Like Macrolophus, it takes water and nutrients from the plant, and with too little prey it will feed on the crop. In short autumn days a British Columbia strain stops laying below about 15.5 hours of daylight, while a California strain is essentially non-diapausing in greenhouses: most of its females kept laying or resumed within two weeks.

Is it established?

Nothing much shows for the first few weeks, because the eggs are hidden inside the plant. Keep counting whitefly on the same leaves, and look for nymphs.

1. WEEK 1Adults settle on the plants; eggs are laid out of sight inside plant tissue
2. WEEKS 3–4Fewer whitefly eggs, then fewer nymphs, as in the Florida cage trial
3. BY WEEK 6Green, red-eyed nymphs of every stage on the plants, as in the Florida cages six weeks after the first release
4. WATCHBugs feeding on the plant where they are many and whitefly is scarce