When your mantis, lizard, or amphibian has outgrown fruit flies, blue bottle spikes are the next size up. These are the soft-bodied larvae of Calliphora vomitoria — about 12–15 mm long, easy to grip, and packed with protein and moisture. They’re the largest feeder we sell short of ordering adult flies, and they bridge the gap between a fruit-fly diet and full-size prey for sub-adult and adult mantises.
“Spikes” is the keeper’s term for fly larvae (maggots) sold as feeders. Don’t let the name put you off — they are one of the cleanest, most nutrient-dense soft-bodied feeders you can offer, and predators that ignore dried or freeze-dried food will hammer a wriggling spike every time.
Who They’re For
Blue bottle spikes suit any predator big enough to handle a 12–15 mm soft body:
- Sub-adult and adult mantises — Ghost, Spiny Flower, Orchid, Dead Leaf, African Twig, Double Shield. Anything past L4 will take them readily.
- Day geckos, crested geckos, and other small lizards looking for a soft, hydrating change from crickets.
- Dart frogs and larger amphibians, and jumping spiders of mature size.
If your animal is still small — L1 to L3 mantis nymphs, jumping spider slings — these are too big. Start with D. melanogaster or D. hydei fruit flies and work up.
How to Feed Them
Tip a few spikes into a shallow dish or place them directly where your mantis can reach. The larvae move enough to trigger a feeding response but can’t climb smooth walls, so they stay put. Dust with a light calcium powder once or twice a week to round out the nutrition — soft-bodied feeders are naturally low in calcium relative to phosphorus, and a quick dusting fixes the ratio.
Want flies instead of larvae? Leave a portion of the cup at room temperature and the spikes will pupate, then emerge as adult blue bottle flies in a few days — a great variety feeder for flying-insect specialists like mantises.
Storage & Shelf Life
Spikes ship in a vented cup with sawdust bedding. Refrigerate on arrival (the door of the fridge, around 4–8 °C) to slow their development if you aren’t feeding them out within 48 hours. Cold holds them at the larval stage for up to two weeks; at room temperature they’ll pupate within a few days. Pull out what you need, feed it, and return the rest to the fridge.
Frequently Asked Questions
What are blue bottle spikes?
Blue bottle spikes are the live larvae (maggots) of the blue bottle fly, Calliphora vomitoria. At 12–15 mm they’re a large, soft-bodied feeder used for sub-adult and adult mantises, geckos, dart frogs, and other insectivores that have outgrown fruit flies.
How big are blue bottle spikes compared to green bottle spikes?
Blue bottle spikes are the larger of the two at 12–15 mm. Green bottle spikes (Lucilia sericata) are 8–10 mm — a half-step between fruit flies and blue bottles, better suited to sub-adult mantises and smaller reptiles.
How do I store fly spikes to keep them from turning into flies?
Refrigerate them. At around 4–8 °C the larvae stay dormant at the spike stage for up to two weeks. Left at room temperature they pupate within a few days and then emerge as adult flies — which is useful if you actually want flies for variety.
Can mantises eat blue bottle spikes?
Yes — any mantis past about L4 (sub-adult onward) will take blue bottle spikes. They’re too large for L1–L3 nymphs, which should be fed fruit flies first. See our feeding guide for stage-by-stage prey sizing.
Ships in a vented cup with sawdust bedding. Refrigerate on arrival to slow pupation if not feeding out within 48 hours.
