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How to identify it
- Adults are dark brown and fully winged. The brown forewings are pale on the basal quarter and have a broad pale area near the tip, so the wings look banded.[1][2]
- The antennae have eight segments, with the first three yellowish to light brown. The tips of the middle and hind shins and most of the front shins are yellow.[1]
- Males are smaller and paler than females, with a yellow thorax and legs. Females are hard to tell from several related Megalurothrips species, so a male specimen gives the surest identification.[1]
- Young larvae are white; older larvae and prepupae turn yellow to orange.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Melon thrips | Shares Florida bean fields with the bean flower thrips, but it is yellowish, with unbanded wings and seven antenna segments instead of eight.[2] |
Where it lives
Native to Asia and found in India, Pakistan, Bangladesh, Sri Lanka, southern China, Japan, Fiji and northern Australia. In the United States it was first found in Florida in 2020, in Miami-Dade County.[1][2]
Biology and life cycle
The life cycle runs through two larval stages, a prepupa, a pupa and the adult. On bean pods, egg to adult took about 9.5 to 11.6 days, fastest on snap bean.[1]
It can reproduce with or without mating. Development speeds up as temperatures rise, but larvae died after hatching above 30°C (86°F) and below 14°C (57°F), and females laid the most eggs at 20°C (68°F).[1]
Adults are most active in the morning, about 8 to 10 a.m., and rest at night. They gather in groups, apparently drawn by a pheromone the males produce, and their numbers climb after the crop is past mid-bloom; larvae peak five to seven days after the adults.[1]
Both larvae and adults prefer flowers to leaves. In snap bean fields in south Florida, the most thrips were found in flowers, then leaves, then pods, and they occurred in clumps.[1][2]
It has been recorded on 28 plant species, mostly legumes: snap bean, lima bean, cowpea, yard-long bean, mung bean, black gram, pea, pigeon pea, peanut and soybean, along with sunn hemp and other legumes.[1][2]
Damage and signs
- Larvae and adults feed on flower buds and flowers, which causes deformed pods and pod drop. When no flowers are present they feed on young leaves and pods.[1][2]
- Losses can be severe. Legume thrips like this one can cut yields by 80 to 100 percent, losses of 13 to 64 percent have been reported in mung bean, and a Florida researcher has observed severe infestations causing total crop loss.[1][2]
- It is one of the carriers of tobacco streak virus, spreading infected pollen on its body to the plants it feeds on.[1]
Health risk
UF/IFAS describes it as a legume pest and plant-virus carrier; it mentions no harm to people.[1]
Control
Traps and physical control
Blue sticky traps attract it best, and sticky traps and water traps both work for sampling. Its aggregation pheromone may one day be used in lures for monitoring and mass trapping.[1]
Biological control
Minute pirate bugs (Orius species) are important predators in Asia, and a parasitic wasp, Ceranisus menes, attacks it in Taiwan and the Philippines. Formulations of Bacillus thuringiensis and the fungus Metarhizium anisopliae have also reduced populations.[1]
Pesticides
Insecticides with different modes of action have given suppression in various countries, but heavy, frequent use harms natural enemies and the environment. Plant extracts such as neem, garlic and ginger suppressed it on mung bean but still need full evaluation. Check UF/IFAS for current Florida recommendations.[1]
Common questions
- What is damaging the flowers and pods on my Florida snap beans?
- In south Florida, the bean flower (Asian bean) thrips and the melon thrips are the main thrips pests of beans. The bean flower thrips feeds mostly in flowers and causes deformed or dropped pods.[1][2]
- When did the Asian bean thrips arrive in the United States?
- It was first recorded in Miami-Dade County, Florida, in 2020, the first record in the continental United States.[2]
- How do I tell Asian bean thrips from melon thrips?
- Asian bean thrips is dark with banded forewings and eight antenna segments; melon thrips is yellowish with plain wings and seven antenna segments.[2]
Sources
- University of Florida IFAS Extension (EDIS), “Bean Flower Thrips, Megalurothrips usitatus (Bagnall), Featured Creatures EENY-777 (R. Khan, D. Seal and R. Adhikari, 2021).” journals.flvc.org/edis/article/view/127931 (accessed 2026-11-09)
- Insects (MDPI), “Within-Plant and Within-Field Distribution Patterns of Asian Bean Thrips and Melon Thrips in Snap Bean (Adhikari et al. 2023, Insects 14:175).” pmc.ncbi.nlm.nih.gov/articles/PMC9960844/ (accessed 2026-11-09)
- iNaturalist, “Megalurothrips usitatus taxon page (order and family).” www.inaturalist.org/taxa/1194376 (accessed 2026-11-09)