Removing the crop from hand-fed feeder roaches

[Katnapper]

I'm wondering if anyone knows, or has heard or read, recommendations about removing the crop (and its contents) of feeder roaches before offering them to mantids? It seems I've read something about it before (recommending it be removed), but cannot remember where, why, or by whom it was suggested.

I would very much appreciate any comments, referrals to reliable sources of information, or personal opinions about the subject... whether it is beneficial and/or recommended or not; and explanations or opinions of reasons why. Answering the poll questions would be helpful and interesting also. Thanks!

 

[Colorcham427]

I'm wondering if anyone knows, or has heard or read, recommendations about removing the crop (and its contents) of feeder roaches before offering them to mantids? It seems I've read something about it before (recommending it be removed), but cannot remember where, why, or by whom it was suggested.

I would very much appreciate any comments, referrals to reliable sources of information, or personal opinions about the subject... whether it is beneficial and/or recommended or not; and explanations or opinions of reasons why. Answering the poll questions would be helpful and interesting also. Thanks!

May you be please define "crop" in this series of questions and such.

 

[PhilinYuma]

I'm wondering if anyone knows, or has heard or read, recommendations about removing the crop (and its contents) of feeder roaches before offering them to mantids? It seems I've read something about it before (recommending it be removed), but cannot remember where, why, or by whom it was suggested.

I would very much appreciate any comments, referrals to reliable sources of information, or personal opinions about the subject... whether it is beneficial and/or recommended or not; and explanations or opinions of reasons why. Answering the poll questions would be helpful and interesting also. Thanks!

This is a seriously interesting question, Katt in that I can't imagine why anyone would go to the considerable trouble of dissecting out all their cockroaches' crops and feeding their mantids a dead roach by hand.

First, for those of us like Brian, who have forgotten our basic insect anatomy, the crop is that area of the insect foregut between the esophagus and proventriculus. Food passes from the mouth, through the esophagus to the crop where carbohydrates are broken down by digestive juices. It then passes through the proventriculus where, in the cockroach, the food is ground by sclerotized plates before passing through the stomodeal valve into the midgut, which we don't have to discuss right now. (Damn! Love that hypertophic matrix!

)

In order to remove the crop, you would have to make an anterio posterior incision through the ventral surface of the thorax and abdomen, remove the fat body, dissect out the crop, making incisions at the distal end of the esophagus and the proventriculus. If you want to avoid the contents of the gut leaking into th body cavity -- rather defeats the purpose of the exercise -- you should tie off the crop for and aft before making the incision.

Mantids have been getting along very nicely for a very long time eating their roaches fat body, crop and all. They do the same with the roaches' cousins, the crickets and grasshoppers. Why not dissect them out too?

Incidentally, you could get the same result by not feeding the roaches for a day or so until the crop has emptied its contents into the midgut. If you remember where you saw this, Katt, I for one would be very interested to know who suggested it.

There are lots of pix of insect guts on Google, but for a very pretty cross section of the cockroach crop and dissected proventriculus to show its "hexaradial symmetry"

see: R.F. Chapman, The Insects: Structure and Function 1998, Cambridge University Press p.39.

O.K. Here's a URL for a dissected cricket showing the crop. http://educatus.com/main/samples/default.asp?lid=801505&scid=8015050020

Sure you want to do this?!

I see that it's 0224. Shouldn't we all be asleep?

 

[Rick]

What would be the purpose? Mantids generally eat around the crop and gut at least on large insects.

 

[hibiscusmile]

good one Phil, such info! As I once said to a stupid someone on having a baby at home " if you have the baby here, how will we suck the stuff out of its nose?" I then replied, the same way they did in Jesus's time! duh!

what, no hospitals, no anaesthesia for the roach?

 

[Katnapper]

I can't remember where I read the suggestion of removing the crop before feeding. I read it on-line somewhere when I was doing exhaustive research on feeder roaches before buying some. But it has stuck with me, and that's what I've been doing. But I'm wondering why it was recommended and I can't remember or find the source. I'm wondering if the contents of the crop add to the nutrition of the mantid's meal? Or are the contents indigestible, possibly containing things which might make them sick, or just not tasty to them, as I've seen them eating around it to avoid it. In the roaches I cut up and use, the crop is rather large, usually with a significant amount of contents. It does take a little extra time and effort, but not too much. It actually comes out pretty easily. I'm just wondering if it's worth it, or a beneficial or detrimental practice... and why.

I've tried feeding the mantids roaches just by putting the appropriate sized ones in the mantids' cages. But they like to hide under the paper towel substrate and do not move very much at all once they find a comfy spot. I've found they are pretty useless as a feeder in that context. But I also find them indispensable as a reliable back-up when having issues with getting or hatching BB or house flies; and a heftier meal for larger mantids that hand feed easily. I haven't bought, bred, kept, or fed any crickets at all since getting my roach colony going.

When I go to hand feed my mantids B. dubia roaches, I usually always pick the adult males and cut them up to appropriate sizes, as there are so many of them and they are relatively large. Plus they have convenient wings to grab hold of with forceps. In my experience, the mantids just balk at live appropriate sized intact nymphs (not cut or crushed with gut juices poking out) when I try to offer them with the forceps. And they won't go after them at all if just left in the enclosure. I get much better results by cutting them up and sticking the creamy whitish colored gut parts on their mouths. They quickly realize it's food and usually start munching and grab right on to the piece.

My method with the adult male dubias is to grab them by the back part of their wings with forceps with my left hand; then with scissors in my right hand I cut off their heads and a little bit of the thorax. Then I turn them over and cut off all the pesky legs, and then the wings. If you cut the head and wings off at just the right point, the crop will usually start poking out of the "neck" opening on its own after about a minute. Then it's usually a really easy procedure to grab hold of it and pull it the whole thing out in one piece, intact, and discard. I use 2 pairs of long forceps and a pair of scissors for the whole process... works very well for me.

But is it a good idea, worth it, or not?

 

[PhilinYuma]

The gut contents of prey are seldom of any value to a predator, be it insect or mammal, though the latter will eat their prey's small intestines.

A number of us have noted that mantid's tend to avoid the crop of their prey, not because it is harmful to them, but simply because it would fill their own crop with useless vegetable food. Plant material tends to be broken down in vegetarian animals by microbes -- gut flora -- that predators do not possess. This, incidentally, is another reason why I find "gut loading" of prey insects to be a total waste of time (sorry, gut loaders!).

It seems that your system works well for you, Katt, and solves the worst problem with feeding roaches, their tendency to hide, or if they can't, remain motionless. If I think that a roach has survived too long, I will nudge it with a stick to get it going. I have also placed small amounts of sticky food, like gravy, high on a twig, so that the hungry roach will climb it to its doom.

I personally don't hand feed any mantis that can feed itself. Doing so reminds me of those poor bears at Yellowstone that have become dependent on the "kindness" of tourists, but then, I have a very poorly developed maternal instinct.

 

[Rick]

I see it like this: they eat their food with the crop intact in the wild so that is how mine are going to do it.

 

[JoeCapricorn]

In my experience, a mantis will eat the crop of an insect depending on the contents and age of material in the crop. If the contents are fresh and young and bitter tasting, the mantis will simply eat around it. The "orange cube" cricket diet would never get eaten and remains of crickets fed to my Chinese mantises last fall would just be bits of wings, legs, and this orange tic-tac shaped thing. The dry gut-load I have is sometimes eaten by the mantis directly or sometimes discarded, but the thing about the crop is when the mantis does get to that part, the entire organ is removed very easily by the mandibles and separated from the body (from what I've seen) - thus, the organ itself is just hanging on the mandibles and many times the mantis tries to nibble at it, but the crop gets unhooked and falls.

I also found with small crickets when ripping them in half (to share 1 cricket between 2 mantids), the crop often comes with the head. I make sure I keep the crop intact, because it does contain important nutrients that I want passed to my mantises. Anything they don't like to eat they will discard. I even have an informal system where every time I split a cricket, I mark down which mantis gets the head and which gets the abdomen, that way next time I split the cricket between these two mantises, I switch what is given to who, so the one who got the abdomen now gets the head and the one who got the head gets the abdomen.

 

[PhilinYuma]

That's a nice description of a mantis avoiding a cricket's crop Joe. What I have a problem with is your statement that you want the mantis to eat the crop, "because it does contain important nutrients that I want passed to my mantises."

This seems to be contradicted by your first paragraph, though I may just have misread it, but I would like you to tell us what important nutrients for mantids are contained in the cricket's vegetable crop contents and where you learned that this is the case.

 

[JoeCapricorn]

I got this cricket feed that contains protein and other nutrients that may or may not benefit the mantis. That's all.

 

[PhilinYuma]

I got this cricket feed that contains protein and other nutrients that may or may not benefit the mantis. That's all.

Fair enough. I wasn't trying to give you a rough time! Actually, there is very little information on the dietary needs of mantids. The gut loading foods for crickets that you can get in pet stores, though, are primarily intended for crickets being fed to vertebrates and contain calcium and trace minerals, as well as vitamins that herps and frogs don't get in their regular captive diet.

At the moment, I can find no evidence that any kind of gut loading, from vitamins in crickets to honey in flies provides any demonstrable benefit for mantids, but I am always open to being convinced otherwise by a good argument and a little evidence!

That is not to say that pollen is not a valuable vegetable protein source used by many insect predators from bees to ladybirds to mantids, whether obtained directly from a plant, as is the case with the first two mentioned, or from eating pollen-dusted insects as in the case of mantids. I have wondered, though, why mantids don't eat the hind legs of bees, which contain the pollen pouches. They're probably not up to date on the latest literature.

 

[JoeCapricorn]

Well, the stuff I have indeed contains calcium. It also contains phosphorus, fiber, fat and salt. My main goal was a protein supplement for the mantises AND crickets. Before, the crickets just nom'd spring mix which does not contain a lot of protein but DOES contain vitamins. Calcium won't harm the mantises and if they do utilize it, they are getting plenty. The fiber may aid digestion as it does in vertebrates, and would be supplied in a natural diet anyway and may be supplied by the spring mix I feed the crix as well.

Secondly this gut-load is being fed to my roaches. I tend to be nervous in trying new stuff with them, since that may have been what killed Shadow last fall - I fed him so much different stuff, including bread, meatballs from a meatball sandwich, Cheez-Its and the Orange Cube cricket diet. But it could've been none of that. All of my roaches are doing well except for Yog-sothoth who died.

 

[sufistic]

Lots of interesting information here! Thanks all.