Caterpillars

Moth larvae that chew leaves and can tunnel into flowers, causing rot. Hand-pick, screen the tent and remove damaged flowers fast.

Symptoms

• Chewed holes and ragged edges on leaves.
• Dark droppings (frass) on leaves below the feeding site.
• Brown, rotting patches inside flowers where caterpillars have been feeding.
• Caterpillars on the plant, often easiest to spot at night with a torch.

Quick checks

• Search the plant at night with a torch.
• Follow droppings upwards to find the caterpillar.
• Look inside flowers for webbing, droppings or brown patches.

How to fix it

1. 1
   Prevention

   Keep moths out

   Fit mesh over intakes and keep the tent zipped.

2. 2
   Physical

   Hand-pick

   Remove caterpillars and egg clusters by hand, checking at night. Cut out any flower damaged by feeding, well past the damage, to stop rot spreading, and bag it.

3. 3
   Biological

   Bt and nematodes

   A Bacillus thuringiensis var. kurstaki (Bt) spray affects only caterpillars and must be eaten, so it works best on young caterpillars with good coverage; use one approved for amateur use in the UK and follow the label, in the growth stage or early flower only. RHS also lists caterpillar nematodes (Steinernema) from biological control suppliers, which need foliage to stay damp to work.

4. 4
   Support

   Help the plant recover

   Once the caterpillars are gone, Monkey Mist can help the plant bounce back from pest pressure in growth and early flower.

Likely causes

• Moths getting in through open doors, vents or unscreened intakes.
• Plants or cuttings brought in from outdoors.

What to avoid

• Don't spray anything onto developing or maturing flowers.
• Don't leave chewed flowers on the plant: they turn into grey mould.

Prevention

• Intake mesh and a closed tent.
• Don't bring outdoor plants into the grow space.
• Check at night if you see small moths.

Monkey products that can help

Monkey Mist

Monkey say it helps plants bounce back from pest pressure. It is a foliar feed, not a pest control. Growth and early flower only.

Ready to use, no mixing. Mist evenly over the tops of the leaves in propagation, growth and early flower only. Safe with the lights on. Never spray maturing flowers.

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Stress

Can help strengthen cell walls, making life harder for leaf-eating pests. Support only.

2 ml per 10 L every week. Always add it to the water first and mix thoroughly before adding anything else.

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Products support a healthy plant. They don't replace fixing the cause.

When to get help

If you find caterpillar damage inside several flowers late in flower, or grey mould follows, email info@monkeynutrients.co.uk with photos.

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