Since I was interested in keeping giant burrowing roaches. I have done some digging around, googling, and surf various forums, no one ever (well.. maybe a few did. But most just say gum leaves not safe, or narrow leaf safe... etc) quote which species of eucalyptus to begin with, which I think is quite meaningless to continue the discussions until we have those information at hand. I have got some info on local species (that's Hong Kong) so far. But please be reminded that there are hundreds of eucalyptus species, some look very similar to each other, so please take great care when researching and especially feed them to your animals.
1. Eucalyptus citriodora which is extremely popular around the world, for its insect repel ability and strong lemon scent, which is most definitely not safe. Its a strong natural insect repellent, and it produce more essential oil (and its oil contain PMD, a chemical for making commercial mosquito repellent) than most other eucalyptus. And their leaves look very much like those narrow leaved ironbark found near giant burrowing roaches. There are people claiming narrow leaved eucalyptus is safe, that's the problem, since many species have narrow leaves, and some are toxic like this one, not even koala touch this stuff.
2. Eucalyptus robusta, Koala eat them, so its a start. But robusta's natural habitat is in coastal area, so I doubt very much its native to Giant Burrowing Cockroach's area. I have collected some dried leaves from local country park. But when I boil or steam them, I still get a very strong gum smell which probably means essential oil content is quite high even dried. I will try various method to get rid of the oil, if I can make it clear of essential oil, at least to a point that I can't smell it when being steamed/boiled/microwaved, I might try it on some roaches and see how it goes. Need more info or experiment.
3. Eucalyptus camaldulensis, and Eucalyptus tereticornis. A fellow in Australia suggested to me that E. tereticornis is probably safe since its widely distributed, and is not aromatic, while E. camaldulensis is a little more on aromatic side, so a little more risky. Unless I have a lot of babies at hand for experiment, I don't think I would try these at all.
4. Eucalyptus crebra (narrow leaved ironbark). The same Australian fellow told me that this is the tree species found in his neighbourhood, where he can also find giant burrowing roaches. Provided his information is correct, this is the single species that is almost certain is safe for giant burrowing roaches. The problem is that since this species isn't aromatic, contain less essential oil than other gums, grow not very fast, and need specific condition to grow. It isn't common outside australia, mostly planted for timber harvest and nothing else. For me, it cannot be found anywhere in Hong Kong, and people in China only grow them in private lands for timber harvest, so I have no access to it. Since its narrow leaved, if people only show their leaves saying its safe to feed roaches that, without naming the species or at least a picture of the bark, others most definitely will mistaken it with lemon E. citriodora and get into trouble.
[added 22/7/2011]
5. Eucalyptus torelliana, according to
bugsed.com that Cadaghi tree leaves are safe for rhino roach, and its actually their favourite food (probably in that particular habitat).
[/added 22/7/2011]
This is not much, I will try to get some more information on this topic and share if I have anything. And sorry if this info isn't useful for other roach species, but I was only interested in feeding them to giant burrowing roaches.
Hope this helps a little.
Cheers
Kenneth