I've heard that it's virtually impossible to get all the pesticides off a strawberry. I guess because they're "aggregate fruit" (made from a cluster of small flowers) the pesticides can get folded into the fruit body as the flower cluster transforms into fruit... or something like that.
Maybe they sensed the pesticide or maybe they just didn't like the acid.
Have you ever fed your dubias mushrooms? The are absolutely insane for them, never seen anything get eaten so quickly by roaches as mushrooms.
I fed all of my roaches strawberries several times. Each time I did I noticed that some were dead especially the hissor colony. After this happened several times I suspected that it was the pesticide on the berries that was killing them. I placed a few in a separate container and feed them again just to see what happened and they were dead in the morning. The dubia did not seem to eat them as well but I did the experiment with them because I did not want to loose any more of my hissers. This is after trying to wash the berries clean prior to feeding. Maybe it was a bad batch I dont know.
I just would not risk it again or maybe try the organic ones.
It has nothing to do with pesticides. What a roach colony will eat is normally dictated by other environmental circumstances (i.e. the temp and humidity in your home, then thier colony bin, tem fluctuations, other items in thier diet, etc.) Most people keep things slightly differently or have differnt habit of watering/feeding thier roaches, so some people will have a colony that eats somethings that others wont. This is normal. Even though it may seem roaches will eat anything, which is partially true, they also have an inclination to eat more of what thier bodies need and less of what they dont. It could be that the strawberries are natually loaded with vitamin C (Ascorbic acid) and the roaches in question wont eat anything that acidic for example.
There are a few other interesting feeding habits that can be read about in the book Cockroaches by Bell, Nalepa, and Roth for those who have it...
I'm going to try the mushroom thing. Try oranges though. Several threads have been started and nobody really knows why, but when you feed them oranges they just drop babies like redknecks on ecstasy. Oranges i'm going to guess are far more acidic than strawberries. I like the pesticide theory. Someone also mentioned that roaches have a symbiotic relationship with bacteria which produce everythig they need but choline and cholesterol. Oranges are a good source of choline. A lot of people suggest high protein diets with dog/catfood. These would naturally have some cholesterol associated with them.
I take that back. strawberries and oranges are about the same acidity.