Lily Borers

About this pest

Lily borers, those unwelcome residents of South African gardens, can quickly turn your blooming beauties into wilting wrecks. Let’s delve into their world to understand why they’re problematic and how to keep your lilies safe:

Physical Characteristics:

• Adults: Brown moths with black and yellow stripes, roughly 20-40mm in wingspan.
• Larvae: Yellow and black striped caterpillars, reaching up to 40mm in length.
• Movement: Adults are nocturnal, flying during dusk and dawn. Larvae tunnel within leaves, bulbs, and stems.

Common South African Names:

• Lemotrondwurm (Afrikaans) – Amaryllis borer
• Lemotrus (Afrikaans) – Amaryllis
• Kaktusluis (Afrikaans) – Cactus bug (also used for other pests)

Why are Lily Borers Pests?

• Plant tissue feeders: Larvae burrow through leaves, stems, and bulbs, disrupting nutrient flow and causing stunting, wilting, and even plant death.
• Wide range of hosts: Target lilies, but also attack other bulbous plants like agapanthus, clivias, and crinums.
• Multiple generations: Females lay hundreds of eggs throughout the warmer months, leading to several generations per year and increased damage potential.

Combatting Lily Borers:

Monitoring: Regularly inspect lily leaves and stems for signs of larvae like holes, tunnels, and frass (insect droppings).

Natural methods:

• • • Encourage natural predators: Ladybugs, wasps, and birds can help control lily borer populations.
    • Neem oil spray: A natural insecticide that disrupts larval feeding and development.
    • Diatomaceous earth: Can create a physical barrier against larvae on plant surfaces.

Biological control: Bacillus thuringiensis (Bt) is a bacterium targeting caterpillars, safe for other insects and humans.

Cultural practices:

• • • Plant resistance: Choose lily varieties with natural resistance to borers.
    • Proper spacing and ventilation: Reduce humidity and promote drying of leaves, hindering egg-laying and larval survival.
    • Soil drenching: Apply soapy water or hot water drench to soil around bulbs to target hiding larvae.

Chemical control: Use selective insecticides registered for lily borer control as a last resort due to potential harm to beneficial insects and the environment.

Remember:

• Early detection and intervention are crucial to prevent significant damage from lily borers.
• Combine multiple control methods for a sustainable approach, prioritizing natural and organic strategies whenever possible.
• Consider the specific lily variety you’re growing and its susceptibility to borers when choosing control measures.

By understanding the biology and behaviour of lily borers and implementing proactive steps, you can protect your South African lilies from these unwelcome guests and enjoy their captivating beauty throughout the season.