Common Cashew Pests — What to Watch

Why early detection matters

Cashew trees take years to mature, and pests can weaken them or destroy entire harvests. Catching pests early means you spray less, save money, and protect your investment.

Common cashew pests in Nigeria

1. Stem and Root Borer (Plocaederus ferrugineus)

What it looks like: Large brown beetle (2-3 cm long). Larvae are white grubs that tunnel into stems and roots.

Signs of damage:

• Holes in the trunk or main branches
• Sawdust-like frass around the base of the tree
• Wilting or dying branches
• Tree becomes weak and may topple over

What to do:

• Check trees monthly for entry holes
• If you find holes, insert a wire into the tunnel to kill larvae, or inject insecticide (e.g., dichlorvos)
• Paint trunks with a mixture of lime and insecticide (carbaryl) to prevent adult beetles from laying eggs
• Remove and burn badly infested trees to prevent spread

2. Tea Mosquito Bug (Helopeltis spp.)

What it looks like: Small green or brown bug (5-7 mm long) with long antennae.

Signs of damage:

• Small brown or black spots on young shoots, leaves, and flowers
• Shoot tips dry up and die
• Apples (cashew fruit) develop black sunken spots
• Reduced nut yield

What to do:

• Scout weekly during flowering and fruiting (peak season: Feb-May in Southwest Nigeria)
• If you see 2-3 bugs per branch, spray insecticide (e.g., imidacloprid, lambda-cyhalothrin)
• Spray early morning or late evening to catch active bugs
• Repeat spray every 10-14 days during peak season

3. Leaf Miner (Acrocercops syngramma)

What it looks like: Tiny moth. Larvae are small white or yellow caterpillars that tunnel inside leaves.

Signs of damage:

• Winding, whitish tunnels (mines) on leaves
• Leaves turn brown and fall off early
• Tree looks weak and produces fewer flowers

What to do:

• Remove and destroy heavily mined leaves
• If more than 30% of leaves are affected, spray insecticide (e.g., dimethoate, profenofos)
• Maintain tree health with proper fertilization (healthy trees resist leaf miners better)

4. Mealybugs (Ferrisia virgata)

What it looks like: Small white, fuzzy insects that cluster on shoots and flower stalks.

Signs of damage:

• White cottony masses on young shoots and flowers
• Sticky honeydew (attracts ants and sooty mold)
• Flowers and young apples drop prematurely
• Reduced nut set

What to do:

• Spray soapy water or neem oil for light infestations
• For severe cases, use insecticide (e.g., acetamiprid, thiamethoxam)
• Control ants (they protect mealybugs). Bait traps or insecticide around tree base.

When to record an alert

Log a pest alert in the Torade app if:

• You find more than 5 entry holes on one tree (stem borer)
• You see 2+ tea mosquito bugs per branch during flowering
• 30%+ of leaves show mining damage
• White mealybug clusters cover multiple shoots

Recording helps you track which trees are affected and when. It also alerts other farmers in your area if you're part of a co-op.

Quick checklist

• ✓ Check trees monthly for stem borer holes (especially during dry season)
• ✓ Scout weekly for tea mosquito bugs during flowering (Feb-May)
• ✓ Look for leaf miner tunnels on young leaves
• ✓ Watch for white mealybug clusters on shoots and flowers
• ✓ Log pest sightings in Torade app to track trends

Next steps

Use the Torade alerts tool to log pest sightings with photos. Over time, you'll learn which pests appear when, and plan your spraying better. Share findings with your co-op to coordinate pest control and reduce costs.