Black Thread Scale

How to identify it

• Adult females are yellow under an elongated, shiny black cover 8 to 10 times longer than wide, about 2 to 3.5 mm long.^[1]
• Under the lifted armor, the body and a whitish lower layer are visible.^[2]

Where it lives

Native to Africa and found in tropical and subtropical areas worldwide; first reported from Florida in 1908.^[1]

Biology and life cycle

Each female produces 20 to 30 eggs; crawlers settle within 24 hours, and the life cycle takes about 30 days.^[1]

Damage and signs

• It attacks more than 50 plant families and 130 genera, including parlor palm, Swiss cheese plant, philodendron, oleander, plumeria and Japanese privet.^[1][2]
• It can be a very serious pest in greenhouse crops and on tropical fruit trees outdoors in Florida.^[2]

Health risk

None to people or pets.^[1][2]

Control

Biological control

Lady beetles and tiny parasitic wasps help suppress it.^[2]

Pesticides

Armored scales like this are susceptible to horticultural oils used as labeled.^[2]

Related profiles

• Scale Insects
• Palmetto Scale

Common questions

What are the thin black lines on my palm leaves?

Possibly black thread scale covers.^[1][2]

Sources

1. University of Florida IFAS Extension (EDIS, Featured Creatures), “Black Thread Scale, Ischnaspis longirostris (EENY-450).” ask.ifas.ufl.edu/publication/IN822 (accessed 2026-10-16)
2. NC State Extension, “Black Thread Scale Insect (PDIC Factsheet).” content.ces.ncsu.edu/black-thread-scale-insect (accessed 2026-10-16)
3. iNaturalist, “Ischnaspis longirostris taxon page (order and family).” www.inaturalist.org/taxa/330225 (accessed 2026-10-06)