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Optimal conditions: humidity and temp for mealworms/superworms

About to pupate my superworms. I can’t find info on optimal humidity. Can anyone give me some numbers?


  • Mealworms is 80 degrees F, 75% humidity. Supers seem to be thriving in this as well.

  • Both temperature and the light to dark ratio have some impact. See the free on-line Korean pdf of (2015) “Growth characteristics of mealworm Tenebrio molitor”; the data charts/tables/figures are actually in English.

    Here’s some orientation. Although in gross terms larvae develop more as temperature trends upward & there are more eggs laid at 29*Celsius the ensuing weight of both the pupae (& adults) goes down.

    And in terms of just eggs actually hatching 17.5C is quite ideal, followed by 25C as second best (for hatching), 22.5C third best, followed by 20C & then 27.5C. In contrast the time spent as an egg is shorter the higher the temperature & lasts a bit more than 2 time longer at 17.5C (14.7 to 15.9 days as egg) than eggs at 27.5*C (avg. 7 days as egg)

    The ratio of light to dark seems to make no difference on the eventual weight of adult yellow mealworm beetles. However that photo-period ratio does cause both different times spent as larvae & how long pupation takes.

    Shorter time is spent as larvae when kept at 14 hrs light : 10 hrs dark. But data shows to get a shorter time spent as pupae it is better to drop to 12 hrs light : 12 hrs dark.

    Then too there is the category of relative yield. In terms of how many come out to eclose 12 hrs light : 12 hrs dark occasions about a 2% greater success rate than when get 2 hrs. of more light (14 hrs light : 10 hrs dark).

    Table 3 of cited research by Kim, et al indicates 25C is a better production temperature than trialed 27.5C ( or lesser temperatures trialed). At 25*C the days developing as larvae was quick (~ 121 - 150 days) & the time as pupae was the most brief (7-10 days).

    What was notable for this temperature of 25C was the pupal weight was the most (avg. 200 mg) & then the ensuing adults both weighed the most & were the largest. Only citing one other trialed temperature for comparison: at 27.5C the average pupal weight = 170 mg & adult weight = 10 mg less.

    17.5C = 63.5F, 25C= 77F, 27.5C= 81.5F, 29C=84.2F ... the cited research employed many more temperatures than those Ihighlighted.

  • Note: any & all italics are unintentional & I have no time to edit the above comment

  • edited September 8

    Hi BugCatcher5, - I don’t rear superworm Zophobas morio & can only suggest you look at Rainer Schultz’s (1996) “El manejo de Zophobas Mario (...) en clima tropicales humidos”. It is in Spanish so for now I’ll point out just a few things without translating a lot.

    The only references to temperature are as follows. Optimum temperature is 24-29Celsius (air conditioned spaces pose low humidity to take into account) & 32C is problematic for Z. morio larvae; while 35 - 38*C is problematic for these beetles. Large bins allow better heat dissipation & although bin sides need only be 12-14 cm (43/4-51/2 in) tall you want another 25 cm (10 in.) of head space for ventilation.

    The Z. morio eggs are 1.2-1.4 mm & new hatched larvae are 2 -2.5 mm. Fig No. 2 & 3 at end of text show designs for egg traps.

    The female Z. morio beetle will climb a 5cm (2in.) galvanized mesh of 8 mm (1/3 in.) pores (“cocada”) to lay 20-60 eggs (of about 400 in lifetime). The male beetles head is slightly wider & the females are bigger; author recommends breeding stock be 70% female & male beetles culled to 30%. After emergence the beetles are immature for 2-3 weeks.

    Author points out that moisture can be conserved in the egg traps by molded blocks of plaster (“yeso Aleman”); see design in Fig No. 3 . And that plantain (banana) peels can be left for an egg laying substrate & hiding place of new larvae.

    Repeatedly the text points out that Z. morio beetles will eat their pupae (especially in high density) . Therefore, as beetles emerge they “... should be taken immediately from the pupation boxes ... give a little humid food (chicken bones or plantain peels) so ... find food & do not need to attack pupae ....”

    Pupal stage is 2-3 weeks. Tactics mention putting pupae atop a max. 4 cm/1.5 in of substrate using 60% “palo podrido” for conserving humidity. This refers to wood/stems (“palo”) rotted (“podrido”) white looking by lignin decomposition due to natural fungi.

    Diet in the text is quite flexible & “... larvae mandible are very strong ...”; depending on larval size. Author recommends all kinds of grains like oat, wheat, rice, old dry bread, feed corn (maize) & plantain peel for larvae.

    Moist food is supplied only for 1-2 days before replacing (mold control) & put in baskets/troughs with mesh above that has holes (“cocada”) wide enough for larvae to get back out of. Author lists green forage grass leaves, local fruit, juices oranges & potato among other things.

    A core diet item recommendation of 70-80% cracked/ground Maiz (corn, suggested as option to replace wheat) & 20-30% soy pieces (mill seconds) is worked up as follows. Make into 3-4 cm balls for refrigeration until fed, using 300 gr. maiz + 200 gr. soy + 30-40 gr dry yeast + 50 gr. milk powder + 80 gr. honey for sticking everything together (moisten dry ingredients 1st, then add honey). When diet ball/pieces that have given are all gone then can replace.

    The Z. morio beetles can be given every now & then chicken table scraps/bones (remove once picked clean), unsalted dried meat/fish & thin slices of hard boiled egg. This kind of food is put in troughs/baskets (“ canasta”) if the beetle bin is covered with no-see um fine netting (finer than mosquito netting) to keep out other insects.

  • Again - italics are entirely unintentional in comment above.

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