Are crickets bad for mantids?
There has been some misconception among mantid keepers that crickets are not a good food source for many species of mantids. Even I am guilty of passing this info along. However, over the past couple of years I have come to see that this, along with many other "myths" about mantids, is not the case.
I used crickets as my main source and often the only source of food for my mantids for many years. I did have a few deaths here and there and once I started keeping many different species of mantids I noticed some would even vomit a black or brown substance and die a few days afterward. After reading various caresheets and getting feedback from a few other breeders I came to agree that it was the feeder crickets I was using. After that, I switched to roaches and flies.
Years later I met someone who kept various mantid species and fed them crickets almost exclusively with no problems. I thought it was kind of odd that they were not getting sick but eventually it hit me. The crickets were very well taken care of. The cricket bins were clean and they were fed fresh food often. This keeps bacteria in the gut of the cricket under control and greatly reduces any diseases the crickets could get due to accumulated droppings.
So, perhaps crickets weren't so bad after all? I tested this by using them as the main source of food for many of my species, although I still was not willing to test them with the more rare species of mantids. I did not have any problems, as long as I kept the crickets properly.
I did however notice one problem. If I fed my crickets carrots, the mantids would vomit a bit. This usually would not kill them, but they did seem to get a little sick. This would happen just about every time with a few species (wahlbergii, desiccata, mendica), especially if I used crickets straight from a petstore or as soon as they arrived in the mail. Most cricket suppliers use carrots for moisture. Now I wait a day or 2 before using new crickets. I gutload them with my own food and use water crystals for moisture. I should also note that I only use light colored, healthy looking crickets as feeders.
This year I decided to give it a try with a couple orchid mantids and my ghosts. The results were great. I can't say for sure that that this was the result of the crickets, but my orchids and ghost mantids laid the biggest ooths I have ever seen. I also fed them roaches and flies, as I normally do, but adding the crickets seemed to give better results.
Anyway, I just wanted to add my two cents about crickets. Kept correctly, they are an excellent food source for mantids. As always though, it is best to vary the diet if possible.