Humidity for mealworms

[GregH]

I set up a mealworm colony about two months ago stocking it with a 50pce container from the petshop. The mealworms looked full-size and I expected them to pupate but they haven't and I see I was wrong about them being full sized as there is now quite a few shed skins but still development time is lot slower in Brisbane than when I was in Los Banos in the Philippines. I'm pretty sure that the temperature is fine now but in winter I'll have to get a heater and their food is probably OK and the carrots I use for water can't be that different but it is the low ambient humidity here that makes me wonder if that is the cause of their tardiness. I think I've seen this mentioned before on the forum so I'm wondering what backyard mealworm culturists use to overcome this problem? I don't have a dedicated insect room with a humidification system but I could get an old refrigerator and do something with it. Any thoughts?

[Danny]

Two options Greg
1. They are taking their sweet time because that's what mealworms do - when you need beetles they are worms and when you need worms they are all beetles. Ambient humidity in QLD seems to be good enough but without controlled temperature it is unpredictable.
2. You may have purchased hormone treated worms (intentional ??? or accidental) which are quite common in commercial stocks in Brisbane and these just keep on growing and never pupate.

I have switch to Zophobas to overcome the first issue as you determine when they pupate, not the weather conditions.

[E Orix]

Isn't Zophobas the really big Mealworm that is too big for the normal range of our Finches.
The normal Mealworms are bred quite successfully at 29D Cel. No added moisture apart from being fed carrot
The medium is either Bran or a Bran/Pollard Mix.
If you are sifting the eggs from the Beetles then Pollard is by far the best.
Getting the worms to pupate can be a problem and at times slow BUT some of the worms purchased in small lots from Pet Shops
seem to not want to change at all,why?? thats up for discussion.

[GregH]

Yes Zophobas are what are sold as super-worms and certainly the latter instars are too big for finches but the younger ones are fine but you have to be fast to catch them at the correct stage. What Danny said about commercial mealworms being treated with Insect Growth Regulators to prevent maturation is a worry as I'm sure that their effects on birds isn't as well quantified. I noticed that the Mortein Fleabomb I used last week has an IGR (Methoprene) in it to prevent flea larvae from maturing into biting adults. There is an extensive literature on the effects of IGRs on mealworms particularly pyriproxyfen. If it's used on commercial mealworms I'm sure that it's to extend the shelf-life but has the added benefit of preventing the likes of me starting my own colony.

That said I just noticed 4 pupae in the box so maybe it's eventually metabolised and I won't have this problem with my next generation.

[fishdance]

Don't increase humidity in Brisbane. Higher humidity encourages molds and mites. I have 80% mesh open lids and thin carrot slices to reduce humidity. I feed quick oats mostly. I have several cultures going if you want a kick start with Beatles or pupae or larvae.