Tribolium confusum or the confused flour beetle.

As many frog keepers I’m always willing to try out a new type of live food. All help is welcome if it comes to completing the food supply we can culture ourselves. I prefer a type live food that can be easily bred ànd harvested and I think I found one.

(1) Fair Trade

Not so long ago I was talking to some befriended frog keepers at an exhibition in Antwerp. Standing next to our showcase was David Rabeau. It is always fun to chat with frog lovers and when the exhibition was coming to an end we exhanged some live food. I gave David some firebrat (Thermobia domestica) in return for some pea aphid (Acyrthosiphon pisum) and flour beetle (Tribolium confusum). At home, I fed my frogs the pea aphids but somehow, the jar of flour beetles got out of my sight, until recently. To my surprise the number of beetles had tripled and all this without my having taken care of the culture.

As it was the first time I got my hands on the animals, I didn’t really know much about them, so, due to the unexpected success, I started looking for some information. I soon hit some interesting internetsites that convinced me that this beetle could be perfect live food for frogs.

(2)What is a confused flour beetle?

Tribolium confusum means as much as the confused flour beetle. They were given this name by mistake. When they were first named, Tribolium confusum was called Tribolium castaneum (the rust red flour beetle) until it was realized that there had been a mistake so the name was changed into confused flour beetle. In Belgium and the Netherlands it is also called rice flour beetle and at fairs it is traded under that name.

The beetles belong to the phylum Arthropoda, class Hexapoda, order Coleoptera.

Their family Tenebrionidae has only three beetles of the genus Tribolium.

(3)Where can you find them?

As is suggested by its name, you can find the flour beetle wherever milled grain products or other feeding products are stored.

Beetle specimen have been found in flour, milled grain, muesli, pasta, crackers and even in dried fruits. It goes without saying that the beetle is considered a pest by the food industry.

At home we can also find them in little rests of old flour. If you want to culture flour beetles you found at home, you shoul be careful. As the confused flour beetle and the red flour beetle live in the same environment, you might easily start breeding both. And the last thing we want is red beetles at home because they can fly.

It’s important to discern the confused flour beetle before we start our culture and as the difference between the two is hardly visible to the naked eye, we will need a magnifying glass. Upon camparison we notice that confused flour beetles have antennae which gradually enlarge toward the tip while the antennae of the red flour beetle have the last three segments of the antenna abruptly enlarged. The antennae of the confused flour beetle resemble a golf club. (see picture)

Culture and harvesting

(4)In order to culture and harvest easily it is wise to start a “mother” culture and some subcultures (see later also). Personally I prefer a culture with a “grafted” portion of beetles to a culture with caught specimens, for the reason I mentioned above.

Every successful culture of live food depends on a good growth medium. I consulted Alan Cann, a colleague frog keeper. I  use strong brown bread flour and sift it to remove the larger flakes of bran because they only get in the way later, at harvesting. For the same reason I replace dried yeast by powdered baby milk, which is, as Alan says, “packed with nutritional goodies”. Also the cheaper white flour can be used. A lot of frog keepers obtain good results with this.

(5)Our growth medium consists of 4 parts sifted flour and 1 part milk powder, although I don't bother to measure the quantities accurately. I keep my cultures in large 1-litre-jars and cover them with lids containing a large, fine-mesh ventilation panel, e.g. petrol gauze or panty. ¾ of the jar is filled with the medium and I also place some kitchen paper towel on top of the culture which the beetles like to climb on. This also makes it easy to harvest the adults. In my experience cultures are most successful at a temperature between 28° and 30° C. It is also important to keep the medium dry in order to prevent mold and mites.

(6)When the jars are ready you can seed them with a number of adult beetles (about 4mm long). Soon they start mating. During their life cycle, which can last up to two years, the females produce 200 to 300 eggs. Most eggs are produced in the first months after pupating.

Larvae leave the eggs within a month, if the temperature is good. Fully grown larvae can be up to 12 mm long and their colour varies from white to beige. They have six almost invisible legs they can use to dig themselves in.

The complete life cycle from egg to pupa requires one to four months, depending on the temperature. When a mother culture is successful, one or more subcultures can be started.

(7)What is the use of a subculture and how do we proceed? You get a subculture when you sift out a portion (e.g. 1/3) of the mother culture, removing all the beetles and pupae (also the bigger larvae may be sifted but that’s no problem). To find the correct mesh some experimenting is necesssary; in shops like “Xenos” you can find all kinds of cheap sieves. After sifting, we put the medium in an other jar and so we have a beetle-free subculture. The sifted beetles can be put back in the starter culture or can be used to start a new culture.

We keep the subculture in the same conditions as the mother culture for two weeks to a month. Then we sift the larvae (use a fine mesh sieve) and feed them. It is essential to sift before larvae have developed into beetles. My pumilios willingly eat the larvae.

(8) But why make an effort to start different subcultures?  Adult flour beetles have glands which realease a pungent gas that frogs don’t like. When the beetles feel threatened they release this distateful smell. It is even said that frogs that have been exposed to the nasty-tasting adult beetles will often refuse to take them again, and may also refuse the larvae. Larvae don’t have those glands, that’s the reason why only the larvae are fed to frogs. I have some frogs in my collection that eat the flour beetles - there are always exceptions to the rule I suppose. I offer the larvae in the shallow top of a film roll tube. As the larvae are not very active, it takes some time before frogs recognize this food supply.

Attention: be careful!

(9) A disadvantage of this kind of live food is that they can cause allergies. Especially  if mites develop in the culture. The best you can do then is to kill the contaminated culture by freezing for 24 hours. Don’t forget that flour beetles are a pest species! To avoid allergic reactions it is necessary to work in an open, well ventilated area. People suffering from allergies or asthma must be extra careful. Alan Cann knows people who had to stop their cultures because of this.

Conclusion

This live food is a welcome varation in the diet of our frogs. Starting a culture takes all in all 15 minutes and you don’t have to do it frequently, so the culture of the flour beetleis not time-consuming compared to the culture of the fruit fly. Worth trying, don’t you think? Success!

 Met dank aan Danny De Mulder voor de vertaling.

Met dank aan de University of Florida voor het fotomateriaal.