1001Crickets

Brown House Crickets need heat and they will seek it out.  I use this fact to my advantage in keeping loose ones under control in my house.  I have never had a problem, just an occasional stray.  In a typical house in the Midwest USA, the normal temperatures are below what these crickets need to breed, let alone grow.

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In my setup, there are heat supplying devices under each container.  The tops have a solid lid that is kept slightly ajar for air exchange and reduce humidity.  I aim to keep the bottom of the containers between 82° and 90° f.  The closer to 90° the faster the development of the crickets. A mere 3° can shave a week off their development time.  Above 95° over time has a negative effect, killing off more and more crickets the higher the temperature becomes over time.  I have accidentally lost some cultures when the heater malfunctioned and the temperature hit 105°f.  Pinheads seem more tolerant of higher heat.  Incubation of the ELBs needs a higher temperature (97°f) directly under it because the medium is an insulator.  The temp under an ELB in the breeding cage can be 95° while the top is only 72°, a temperature gradient over 2.5" thickness.  Eggs typically are within the top 1/2 " (1.5cm) of the medium. 

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Now for the ambient (air) temperature.  Being in my basement, there are no sudden heat changes.  In the summer the air temperature is around 78° in July,  66° in January.  

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Crickets seem to need at least 65° f to survive, let alone develop.  When a culture is more mature than I would like it to be at this time, I take it off the heated base and into the cooler air temp to slow development.  They somewhat survive (death rate increases) and development slows down.  I put some in a 50° f environment once for a few days, and will never try this again.  They lost the use of their hind legs and died off within a week in 66° temps.

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In December of 2017 I discovered by accident how important the ambient air temperature is.  I took a 10 day vacation overseas and turned down the thermostat on the 1st floor from 68° to 62°. The neighbor took care of the crickets for me.  Even though the temperature under the breeding cage and hatching cages remained the same, the ambient air temp fell.  I do not know how cold it became,  I suspect closer to 62°.  The effects were quickly seen in the hatching cage.  Normally this cages was restarted every 3 days, else it overloads the rearing cage.  The first time it needed changed was 4 days after I left, then next time was 6 days later.  The heat was turned up to 68° the same day the cage was restarted, anticipating our return.  The next change was 4 days and quickly returned to 3 days.  Note the lids for both the breeding crickets and the hatching crickets are not solid, but mosquito net panels to reduce humidity and plenty of fresh air, else the ELB mold quickly.  Ambient air temps have a greater impact on these.

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In the summer of 2018, the room where the hatching crickets are was closer to 80° f because of how we were using the whole house AC and ventilation to draw cool air from the basement, warming it up.  No AC is blown into the basement.  I notice the ELBs were now done hatching in 3 weeks instead of the normal 4 weeks..  I also suspect a higher fecundity (more eggs per cricket) as I reduced the breeders from 34 to 24 to reduce the numbers I was raising,  This had little effect, the final weight at the end of the raising time dropped just a little, nowhere near 1/3 decrease I expected.   

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Another accidental occurrence happens when I keep a rearing containers on the basement floor under the table that has the rest of the cultures on it.  The containers are in a cardboard box to help retain heat. The lid is slightly ajar for fresh air. Now and then I will find an older cricket among the 14 day old pinheads   These intruders are the ones that escaped while I was changing their cages.  Escape happens and I can't always catch them.  The crickets are seeking out heat mainly, but the food and water availability are probably why they stay. They could have easily jumped out.  One time I had an empty box (no paper, food, or water, just the heat) waiting for the next brood and I found an adult cricket in the box.   So they are seeking heat.

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