Fruit Fly Strains, Sizes, and Care: A Complete Guide

Fruit flies are the default staple feeder for jumping spiderlings, tarantula slings, mantis nymphs, dart frogs, mourning geckos, and pretty much anything too small to handle crickets. But "fruit fly" isn't one thing — there are two species in common use, several strains within those species, and a real difference in size and production speed between them. Here's how to pick the right one, keep a culture alive, and actually use it to feed.

The Two Species

Drosophila melanogaster — the smaller, faster-producing species. Adults run roughly 1/16 inch (about 2–3mm), making them the standard choice for the smallest feeders: jumping spiderlings, tiny tarantula slings, first-instar mantis nymphs, and thumbnail dart frogs.

Drosophila hydei — noticeably larger, roughly 1/8 inch, with 2–4 times the mass of melanogaster. Better suited to animals that have outgrown melanogaster but are still too small for house flies or pinhead crickets. Hydei cultures take a bit longer to get going and produce fewer flies overall, but each fly is a bigger meal.

Care is essentially identical between the two — same temperature range, same media, same handling. The choice comes down to what you're feeding.

Strains We Carry

• Common Melanogaster — the standard wingless melanogaster. Reliable, fast, good all-around starter fly.
• Golden Delicious Melanogaster — a melanogaster strain, same size class as Common, often preferred for its coloring and consistency.
• Turkish Glider — a winged (not wingless) melanogaster variant. Unlike wingless strains that just crawl, Turkish Gliders can glide short distances, which makes them a more active, attention-grabbing feeder for picky eaters. Still flightless in the sense that they can't sustain flight — just short hops and glides.
• Black Hydei — standard dark hydei, the larger-bodied option.
• Golden Hydei — a lighter-colored hydei strain, same size class as Black Hydei.

None of these fly. All are bred to be either wingless or flight-incapable, so a culture won't turn into a loose-fly problem in your home the way wild fruit flies would.

How to Keep a Culture

Temperature: 75–78°F is the sweet spot for melanogaster strains; hydei tolerates a similar range, roughly 70–80°F. Below 70°F, production slows noticeably for either species.

Humidity: Aim for 60–80%. The media itself holds most of the moisture a culture needs — you're not misting these like a fruit fly bottle in a lab, just keeping the room from being bone dry.

Timeline: Melanogaster strains typically show larvae within 4–6 days and start producing adult flies around day 11–13, with production continuing for roughly 18–23 days before tapering off. Hydei runs slower on both ends — larvae around day 8–12, production starting closer to day 19–22, but often continuing productively past day 35–40. This is the main practical tradeoff: melanogaster gives you flies faster, hydei gives you a longer-running culture once it gets going.

Mold and mites are the two things that kill cultures. Keep the culture container's lid on properly (vented, not sealed), don't over-moisten the media, and don't set new cultures next to old ones that show any sign of mite contamination — mites will jump containers.

Starting a new culture: Don't run a single culture down to nothing before starting the next one. Start a new culture when your current one is about a week or two into production, so you always have an overlapping supply and never end up with a feeding gap while a new culture gets going.

How to Use a Culture for Feeding

Let it establish first. Give a new culture a few days after flies start emerging before you begin harvesting heavily — pulling flies too early can stunt the colony before it reaches full production.

Harvesting flies: Tap the container gently to knock flies to the bottom away from the opening, then either pour a portion directly into the enclosure or tap some out into a smaller feeding cup. Working over a tray or sink helps catch any that get away.

Dusting: This applies mainly if you're feeding dart frogs or mantids — supplementing with calcium or vitamin powder right before feeding. Put the flies you're about to use in a small container with a pinch of powder, swirl gently to coat them, then feed immediately; flies groom the powder off quickly, so this isn't something you can do in advance and hold. Spider keepers generally skip this step — most spiders and slings don't need dusted feeders the way dart frogs do.

Don't overfeed the enclosure. Add only what your animal will eat in a session. Uneaten flies left in an enclosure will wander, and if there's anything for them to lay on, you can end up with an unwanted mini-culture inside the tank itself.

Quick Reference

	Melanogaster (all strains)	Hydei (all strains)
Size	~1/16"	~1/8"
Time to larvae	4–6 days	8–12 days
Time to first flies	11–13 days	19–22 days
Productive window	~18–23 days	18–20+ days, often past day 35
Best for	Smallest feeders (spiderlings, tiny slings, tiny mantis nymphs, thumbnail frogs)	Slightly larger juveniles that have outgrown melanogaster