Sunday: I've decided to remove the two discolored caterpillars from the rearing boxes and to give them a box of their own with milkweed leaves. At 3:00 pm. I fed them four milkweed leaves that I cleaned with 10% bleach solution. They are in a rearing box set-up that I have used successfully for many years. I placed the leaves gently on top of the caterpillars. Immediately they became active. One began eating within the first minute, the second began eating within the first 5 minutes. At the present time they are resting.
I am now thinking that before we introduce milkweed to the other containers, perhaps we should adjust the temperature. During the day, we've been able to keep the temperature at 70 degrees in the classroom. At night, it has most likely been 68 degrees. If we brought the temperature up to the mid-seventies, perhaps we will observe some change in the caterpillars' level of activity and interest in the food. Changing the temperature is something we can do without altering the Plan B set-up.