Who is eating my leaves and how to kill it?

Based on the patterns visible in the close-up images — especially the tiny, irregular, squiggly or serpentine trails and circular holes in the leaves of your Do-Si-Dos plant — this is very likely leaf miner damage, not caused by a chewing insect like a caterpillar or beetle, but by larvae (usually of flies or moths) that burrow inside the leaf tissue. 🔬 What are Leaf Miners? Leaf miners are larvae of various insects (mostly flies from the Agromyzidae family) that live inside the leaf layers and create tunnels or mines. Their damage looks like: White or yellow squiggly lines Blistered or transparent patches Small circular entry/exit holes (as you can see in your photos) They are protected from Neem oil, because Neem works on contact or ingestion — and these pests are inside the leaf, not on the surface. ❓ Why Only the Do-Si-Dos? Some strains are more palatable or vulnerable due to leaf structure, terpene profile, or nutrient makeup. Leaf miners can be strain-specific in their preference, especially when populations are small. ✅ How to Treat Leaf Miners (Better Than Neem) Here’s a proven, multi-step strategy: 1. Remove & Destroy Affected Leaves Immediately remove all leaves showing mines or trails. This halts the current life cycle (the larvae will pupate soon and reinfest). Dispose far from your garden (don’t compost). 2. Apply Spinosad or BT (Bacillus thuringiensis) Neem won’t work well on leaf miners inside the leaf. Use Spinosad (natural bacterial insecticide) or BT — both safe for cannabis and organic. Spray in the evening or early morning to avoid UV degradation. Brands: Captain Jack’s Deadbug Brew (Spinosad), or BT Thuricide. 3. Sticky Traps (Yellow Cards) Adult leaf miner flies are tiny black flies — attracted to yellow sticky traps. Hang near the plant canopy to trap adult flies and reduce egg-laying. 4. Prevent Future Infestation Consider covering the plant with fine insect mesh (like Agribon or anti-insect netting). Keep checking for new mines daily for 1–2 weeks. Bonus: Beneficial Predators You can introduce parasitic wasps (Diglyphus isaea) — they lay eggs inside the leaf miner larvae and stop the cycle biologically. Available online from biocontrol suppliers (often used in greenhouses). 🔁 Summary for You (TL;DR): Problem Leaf Miner Larvae (likely Agromyzid fly) Symptoms Serpentine lines & circular spots on leaves Neem effective? ❌ No — larvae are inside the leaf Best treatment Remove damaged leaves Apply Spinosad or BT Use yellow sticky traps Optional Introduce beneficial parasitic wasps Location note Northern Germany = moist climate, higher miner activity