Pest profile

Cactus Moth

Cactoblastis cactorum · Lepidoptera: Pyralidae[2]

The cactus moth is a South American moth whose caterpillars bore into prickly pear pads; spreading along US coasts, it threatens native and rare Opuntia cacti.[1]

Cactus moth caterpillars, orange with black bands, inside an opened prickly pear pad
Cactus moth caterpillars, orange with black bands, inside an opened prickly pear pad. (c) vinicius_s_domingues, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Moths have a wingspan of 22 to 35 mm, grayish-brown forewings with distinct black lines, and white hind wings.[1]
  • Eggs are stacked like coins into an 'egg-stick' attached to a cactus spine.[1]

Where it lives

Introduced to Florida several times, it has spread along the Atlantic and Gulf coasts as far north as Charleston, South Carolina, and west to Louisiana.[1]

US map: public records from 7 states since 1990 (GBIF).

Biology and life cycle

Females lay an average of 75 eggs, up to 140 or more, in each egg-stick; hatching larvae crawl onto a pad and burrow into it.[1]

Larvae do poorly on prickly pears with tough skin, getting stuck in the mucilage.[1]

It was introduced to Australia in 1925 to control invasive prickly pears and reclaimed 16 million acres in Queensland.[1]

Damage and signs

  • It could destroy native Opuntia; rare Florida Keys prickly pears are on the threatened list.[1]

Health risk

It feeds on cacti; UF/IFAS mentions no risk to people.[1]

Control

Biological control

Trichogramma wasps parasitize egg-sticks in north Florida, and the sterile insect technique is a possible tool.[1]

When to call a professional

No satisfactory chemical control is known, and widespread spraying isn't recommended because of rare butterflies; efforts focus on quarantine and biological control.[1]

Common questions

What is eating the inside of my prickly pear pads?
In the Southeast, it may be the invasive cactus moth, whose caterpillars burrow into the pads.[1]
Can I spray for cactus moth?
UF/IFAS knows of no satisfactory chemical control and doesn't recommend widespread spraying.[1]

Sources

  1. University of Florida IFAS Extension (Featured Creatures), “Cactus Moth, Cactoblastis cactorum (EENY-056).” edis.ifas.ufl.edu/publication/IN213 (accessed 2026-10-06)
  2. iNaturalist, “Cactoblastis cactorum taxon page (order and family).” www.inaturalist.org/taxa/199409 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.