The Fruit Fly Culture Jar is a reusable glass jar with a vented lid, a spiral Fly Ladder insert, and a threaded spout that takes either a Vented Cap or a Feeder Nozzle. This guide shows every part, how the pieces fit together, and when to use each topper. For mixing media and seeding flies, see our full Creating Fruit Fly Cultures guide.
Two Toppers, One Spout
Both toppers screw into the same threaded spout, so you can swap them any time without taking the lid off the jar.
- Vented Cap: keep this on while a culture is building up. It closes the spout while letting the jar breathe.
- Feeder Nozzle: screw this in when the culture is producing and you're ready to feed. The narrow tip lets you dispense flies directly into smaller enclosures through a vent or feeding port. The small Nozzle Tip screws onto the end to close it when you're not dispensing.
Every jar includes the Vented Cap. The Feeder Nozzle is included when you choose the feeder nozzle option, and is also sold separately as a Feeder Nozzle Attachment that fits jars you already own.
What's in the Box
To keep the package compact, we ship the jar with the Vented Cap installed and the Feeder Nozzle stored upside down inside the center of the Fly Ladder.
The Parts
| Part | What it does |
|---|---|
| Glass Jar | Wide mouth mason jar, 16 oz or 32 oz. The culture media goes in the bottom. |
| Fly Ladder | Spiral insert that stands in the media and gives flies and pupae plenty of climbing surface. Replaces excelsior or coffee filters. |
| Vented Lid | Screws onto the jar like a standard canning band. Vent slots let the culture breathe while keeping flies in. |
| Spout | Threaded tube that passes up through the lid. A notch in its flange locks onto a key under the lid so it can't spin. Toppers screw into the top of it. |
| Lock Ring | Ring that threads onto the spout and clamps it to the lid. Keep it snug. |
| Vented Cap | Closes the spout while a culture builds up. |
| Feeder Nozzle | Tapered nozzle for dispensing flies into enclosures. |
| Nozzle Tip | Small threaded cap that screws onto the end of the Feeder Nozzle to close it. |
How the Lid Goes Together
The spout inserts from underneath the lid and the Lock Ring threads onto it from the top, holding everything tight. The Vented Cap and Feeder Nozzle share the same threads, so either one screws into the top of the spout.
Lining Up the Spout Key
There's a small triangular key on the underside of the Vented Lid and a matching triangular notch in the spout's flange. When the notch sits over the key, the spout can't turn, so it won't spin loose when you tighten or loosen the Vented Cap or Feeder Nozzle.
- Push the spout up through the lid from underneath, turning it until the notch in the flange drops over the key and the flange sits flat against the lid.
- Thread the Lock Ring onto the spout clockwise and tighten it until it's snug. A loose lock ring lets the spout lift off the key and spin when you turn a topper.
Tip: If the spout turns when you unscrew the cap or nozzle, check that the notch is seated on the key and snug up the Lock Ring.
How to Use It
1. Unpack the jar
Unscrew the lid and lift out the Feeder Nozzle (if your jar came with one). Set it aside until you're ready to feed. Take the Fly Ladder out too, so you can mix media in the empty jar.
2. Start a culture
Mix your fruit fly media in the bottom of the jar, push the Fly Ladder into the media, and let it cool completely before adding flies. Screw the lid back on with the Vented Cap installed. Full amounts, timing, and tips are in our Creating Fruit Fly Cultures guide.
3. Leave the Vented Cap on while the culture builds
Keep the Vented Cap in the spout while larvae develop and the first new flies appear. Depending on species and temperature, that usually takes 10–30 days.
4. Swap the cap for the Feeder Nozzle
When the culture is producing and you're ready to feed, unscrew the Vented Cap and screw the Feeder Nozzle into the spout. The lid stays on the jar the whole time.
5. Feed
Tap the jar gently on a table to knock flies down, unscrew the Nozzle Tip, and tilt the jar to dispense flies through the nozzle into your enclosure or a dusting cup. Screw the tip back on when you're done. Its threads are small, so turn it gently.
Prefer to shake flies out without the nozzle? Just unscrew the Vented Cap and dispense straight from the open spout.
Care and Cleaning
Parts are 3D printed in PETG. Hand wash with warm water and soap, or a water and vinegar solution. Do not put plastic parts in the dishwasher. The glass jar can be washed normally. For a thorough cleaning, unscrew the Lock Ring to separate the spout from the lid. When you reassemble, seat the spout's notch on the key and tighten the Lock Ring snugly. Colors of printed parts vary.
Sizes, Parts, and Add-ons
- The graphics on this page show the 16 oz jar. The 32 oz jar uses the same lid, spout, and toppers with a taller Fly Ladder.
- Lost a piece? Pick up a lid, spout, or Fly Ladder from Replacement Parts.
- Add a Feeder Nozzle Attachment to jars you already own.
- Prefer deli cups? Our Fruit Fly Culture Lid for 32 oz Deli Cups also takes the Vented Cap and Feeder Nozzle.
Shop the Fruit Fly Culture Jar
Designed and 3D printed in St. Louis, MO.