The middle option in the fly-larvae feeder lineup. Lucilia sericata spikes are smaller than blue bottle spikes (8–10 mm vs 12–15 mm) — the right step up from fruit flies for sub-adult mantises and small reptiles that need more substance than a fruit fly but can’t yet handle a full-size blue bottle.
If you’ve ever watched a growing mantis ignore fruit flies it has clearly outgrown, this is the feeder that fixes it. Green bottle spikes give a meaningful meal in a single soft-bodied package, trigger a strong feeding response, and won’t escape the enclosure.
The Feeder Size Ladder
Soft-bodied feeders work best when you match prey size to your animal’s stage. Green bottles sit right in the middle of that ladder:
- D. melanogaster (1.5–2 mm) — L1–L2 mantis nymphs, spider slings, froglets.
- D. hydei (2.5–3 mm) — L3–L4 nymphs and small predators.
- Green bottle spikes (8–10 mm) — sub-adult mantises (≈L4–L5) and small-to-medium reptiles.
- Blue bottle spikes (12–15 mm) — adult mantises and larger lizards or amphibians.
A good rule of thumb: prey should be roughly the length of the mantis’s head, or a little shorter. When in doubt, size down — a mantis will happily take two smaller feeders, but an oversized one can be refused or cause a bad feeding response.
How to Feed Them
Drop a spike or two near your mantis or into a shallow feeding dish for reptiles. The larvae stay where you put them — they can’t climb smooth enclosure walls — so there’s no chasing escapees. Dust lightly with calcium a couple of times a week to balance the calcium-to-phosphorus ratio, which all soft-bodied feeders need help with.
Prefer adult flies? Let part of the cup pupate at room temperature and you’ll have flying green bottle flies in a few days — excellent enrichment for flying-insect specialists.
Storage & Shelf Life
Green bottle spikes ship in a vented cup with sawdust bedding. Refrigerate on arrival at around 4–8 °C to keep them at the larval stage; cold holds them for up to two weeks. At room temperature they pupate within a few days. Take out what you need and return the rest to the fridge.
Frequently Asked Questions
What are green bottle spikes?
Green bottle spikes are the live larvae of the green bottle fly, Lucilia sericata. At 8–10 mm they’re a medium soft-bodied feeder — bigger than fruit flies, smaller than blue bottles — ideal for sub-adult mantises and small-to-medium reptiles.
Are green bottle spikes the right size for my mantis?
They suit roughly L4–L5 (sub-adult) mantises. L1–L3 nymphs should be on fruit flies; full adults can move up to blue bottle spikes. Prey should be about the length of the mantis’s head — size down if unsure.
How long do fly spikes last?
Refrigerated at 4–8 °C, green bottle spikes stay usable at the larval stage for up to two weeks. Left warm, they pupate in a few days and then hatch into adult flies, which you can feed out for variety.
Do I need to dust feeder flies with calcium?
It helps. Soft-bodied feeders are naturally low in calcium relative to phosphorus, so a light dusting once or twice a week keeps growing mantises and reptiles in good shape. See the feeding guide for a full schedule.
Ships in a vented cup with sawdust bedding. Refrigerate on arrival to extend usable life.
