Thanks for your interest and comment. I’ve had lots of similar feedback over time…I assume pesticides, toxic species and the like are at the root of your concerns? I’ve written a 2 Part article that addresses these and related issues; please look it over and let me know what you think when you have a chance. Care is needed, but there are many benefits as well. During my years at the Bronx Zoo, wild caught invertebrates were a regular part of the diets of many of our reptiles, amphibians and birds, and the same holds true in other major zoos…please see this article for further details.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

Best regards, Frank Indiviglio.

Well, in Japanese beetles you’ve hit on an insect that is in somewhat of a gray area for me…surprised and happy that you brought them up, as have been meaning to address the matter in a short note.

Due to a lack of natural predators and competitors in North America, these introduced beetles do build up huge populations. I’m not aware of any toxins/disagreeable taste, and indeed have fed them to monitors, tegus, plated lizards, wood turtles and other robust reptiles. Chitin levels are likely within the normal range for beetles, which should be fine unless they formed the bulk of an animal’s diet. Pheromone-based traps are an ideal collection method.

One problem is that there are a great many insecticides geared specifically for Japanese beetles. While secondary poisoning is supposedly not a concern with the latest generation of insecticides, I’m not quite convinced (not at all as regards rodenticides, incidentally). Collecting in pesticide-free areas is safe as regards most insects. but Japanese beetles disperse widely and cover great distances with their powerful wings, so there may be a concern.

An incident occurred some 15-20 years ago that again set off some warning bells re these insects. A colleague reported losing 2 frogs, both long term captives (African clawed frog, 15 years, American bullfrog, 7 years) within a few hours after having fed them Japanese beetles (6 and 12 beetles, respectively). He refrigerated the bodies, but only after they had been exposed to warm temperatures for a time. I retrieved the animals and had them autopsied at the Bronx Zoo. Unfortunately, the heat compromised the results, but it seemed clear hat toxicity was not an issue. However, both frogs bore cuts and other injuries along their digestive tracts, perhaps caused by the beetles’ strong, spiny legs.

Odd in a way, as bullfrogs occassionally consume tooth-bearing rodents, bats and other formidable prey, and other species (African bullfrogs) consume scorpions, centipedes and venomous snakes. However, Japanese beetles are not native, and certainly are better protected by spines and vigorous escape behaviors than are native beetles. Perhaps it was just the wrong combination of size, prey mobility and such that rendered them fatal in this case.

Lizards and turtles tend to crush/tear insects before swallowing, while frogs take most prey down while it is still very much alive (cicadas continue their distress calls for a few seconds after being swallowed by bull and green frogs). Their digestive enzymes are quite strong, and quickly subdue normal prey species, but again perhaps the Japanese beetles are somehow resistant, at least for a time.

Years later, a co-worker reported that his beagle expired after having consumed approximately 1,500 Japanese beetles!

So, I’m left uncertain, but suggest erring on the side of caution and avoiding Japanese beetles – meaty and abundant as they may be – until we learn a bit more (or you learn a bit more!).

Thanks for spurring my thoughts on this interesting topic.

Good luck and please keep me posted.

Best regards, Frank Indiviglio.

Nice to hear from you again. I’m glad you enjoyed the article, thanks for letting me know. Collecting insects with this technique is very rewarding – provides a great catch and is quite allot of fun.

I’m sorry, I should have been clearer concerning the tent caterpillar photo…I meant to use it to illustrate some of the “hairy” caterpillars that are best avoided as pet food. I did experiment with them a bit…African bullfrogs take them right down, but I’m not sure how safe it would be to use them long term. Most lizards and frogs refuse them, due to the irritating hairs.

Tent caterpillars are not, by a long shot, the most noxious meals taken by African bullfrogs…for a few strange-but-true stories, please see my article An Appetite for Cobras.
Happy hunting…please let me know how it goes.

Best regards, Frank Indiviglio.

There are plenty of tent caterpillars around here, but I never thought about feeding them to my reptiles. Interesting.