Paper bag experiment is done.

jrcagle(z7 MD)August 25, 2009

My experiment with raising cats in paper bags is over, and I thought I'd reflect on the pros and cons of it. The reader should keep in mind that Sandy (butterflymomok) is the expert on this and probably has solutions to some of the issues I raise below.

My procedure: take small cats or eggs on whole leaf off of plants and put into plastic glad containers, 10 cats/container. Strictly regulate age so that all cats are +/- 3 days of each other. Leave them in until 3rd instar, replenishing food and counting cats daily.

At 3rd instar, transfer cats to paper bag, with whole plant sprigs in water pics, supported by Dixie cup. Check food and count cats daily. Cats should pupate on side of bag (but see below...).

At pupation, cut small paper square around the cremaster and tape the paper to top of cage or other container for pupation.


Results: I raised 21 caterpillars in bags until the last instar and into pupation in about half of the cases.

The biggest pro to the bag method is hygiene. When raising in cages, I feel nervous about the possibility of NPV or OE making it through the cage. In bags, a disease is self-limiting. This is a large advantage for those whose populations are 100+ cats.

Other pros: Surveys were easy to make accurate. The cats were well-protected (0 losses). Cat poop is contained and does not need to be cleaned out, since the bag is discarded after the cats pupate.

The biggest con is population control. Because the caterpillars sometimes migrate to the top of the bag, and because I'm hesitant to move a stationary cat lest he be preparing to molt, I ended up not being able to secure the bags tightly. In other words, I had to trust that the cats would stay near their food source.

Twice, that assumption failed. I had one escapee two days ago (15 minute search; he had crawled up the china hutch). Then, today, I came home and found that six (!!) cats had escaped looking for places to pupate. One attached to the wall, one to the china hutch, one to another paper bag, and another to my microscope. As a result, I transferred the 10 remaining last-instar cats into the cage for safe-keeping.

Sandy double-folds the bags and clips them with document clips, but I was not comfortable making a tight seal with cats near the top. So ...

Additional cons: We don't really have a lot of inside storage space, and I don't trust bags outdoors what with wind, water, and sun. Also, getting food in and out of the bags is less convenient than in the cage.

Actually, food is a big issue. In the cage, I can "load up" a group of 21 cats with 7 or 8 stems of milkweed on a couple of Glad containers and then basically check every day to see that the food is still ample -- a 2 second scan, or 2 minutes if I do a cat count. Adding new food is simply a matter of adding a new stem to the container or putting a new container in the cage.

In the bags, I have to open each bag, count the cats, and pull the Dixie cup out in order to change out the food -- which is challenging in the limited space of the paper bag, especially when there are two chrysalises on the side and three large cats on foodplants.

Finally, the process of transferring pupae from bag to cage is clumsy, and I don't entirely trust the tape to hold the pupae to the cage.

So in the end, I will hybridize the methods. I'm totally sold on keeping small cats in containers; but after 3rd instar, I'm going to transfer them to cages.


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It's always interesting to see how other people raise cats.

I use fish tanks with newspaper on the bottom, soda cans with water for the milkweed and cover it with cloth and a wire screen. I have a 2nd fish tank I use to transfer them over to every couple of days depending on how messy the tank is.

    Bookmark   August 26, 2009 at 5:51AM
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I didn't put the milkweed cuttings in water; putting fresh stems in 2x a day worked well and the cuttings did not wilt any quicker than they did in water. Keep in mind I was using A. incarnata and not curassavica.

I double folded the top and secured with clothespin; no escapees.

I tape my chrysalids to an outdoor window on my porch which works beautifully and isn't that hard to clean. Never had a fallen one so far. I can see the potential for your concern in taping them to cages. I also use packaging tape rather than scotch tape. I also cut fairly large portions of bag so the tape overlap thus tape thus greater security to prevent hazard of falling.

The frass dries out quickly with less humid conditions, and I easily tip the bag over paper towels to assure no one falls out with the frass that I might miss in the process and if they do, I can see easily find them.

The bags are a great method to use particularly for Monarchs. I have only raised a few cats using this method so don't know how it would work on a larger scale.


    Bookmark   August 26, 2009 at 7:52AM
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butterflymomok(7a NE OK)


Susan shared everything I would have added. I do use curassavica, and the leaves stay fresh until the butterflies eat them. I just throw in a hand-full of leaves 2X a day and usually dump out frass once a day. I cut the sack open and tape the whole sack to my eclosing container. If not feasible, I cut out a large area around the chrysalis. I need to look up the picture. I limit the number of cats to 6 to a sack.

The advantage to raising them this way is the climate control issue. The sacks allow light, but stay dry. The sack surface provides good traction for newly eclosed BFs.

However, each person should find the method that works best for them.


    Bookmark   August 26, 2009 at 10:52AM
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It sounds like the key is not keeping the milkweed in water. I didn't use paperbags, but I also didn't keep my curassavica in water. They ate it fast enough that it wasn't a problem. Even when it was wilted, it was still okay for them to eat. Probably not perfect, but then my incarnata was wilted, in situ, in hot weather. Think I will try it next year as I can't keep them in cages and I love containers but it is messy.

    Bookmark   August 26, 2009 at 6:06PM
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butterflymomok(7a NE OK)

Today I found 45 Monarch eggs. So, I will be utilizing the paper sacks again. These are destined to be released at a local wedding. No, I am not being paid for them! They are a gift.


    Bookmark   August 26, 2009 at 9:18PM
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KC Clark - Zone 2012-6a OH

Did not want to see this useful info drop off the list.

    Bookmark   June 29, 2011 at 2:02AM
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Thanks, KC.


    Bookmark   June 30, 2011 at 7:32PM
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I also saw that Edith (of Shadyoak butterfly farm) demonstrated using a pizza box. I thought this was brilliant! Lots of room for caterpillars and they pupated on the top of the box. I wonder if they like sausage or pepperoni?

    Bookmark   June 30, 2011 at 8:31PM
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butterflymomok(7a NE OK)

Thanks for the chuckle, Elisabeth.


    Bookmark   June 30, 2011 at 8:56PM
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KC Clark - Zone 2012-6a OH

Bump for folks who don't know about paper bags.

    Bookmark   September 13, 2013 at 2:42AM
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butterflymomok(7a NE OK)

I'm still using paper bags for part of my caterpillars. Mostly because I can give a bag of chrysalides to a child (or adult), and they think it's the best present in the world.

Did a presentation on Native Plants and Butterflies for our local Native Plant Society on Monday night. Nice crowd--had to bring in chairs--so I felt pretty encouraged about the interest out there. I brought a bag of pupae and gave it to a teacher in the group. She was HS Botany/Biology, and had some students with her. Didn't know all this, but had decided before hand to see if I could find a teacher in the crowd when I was asking questions to narrow down the group to one person to receive the "grand prize". Had a great time, and hopefully convinced some folks to plant for the butterflies.

    Bookmark   September 13, 2013 at 4:34PM
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docmom_gw Zone 5 MI(5)

How fun to get such positive response to your presentation. And it's nice to be able to give away pupae, since the recipient can't do too much damage at that point. But, they still get the advantage of seeing the emergence of the butterflies. Though, you know you've ruined whatever lesson plan she has ready for the day they start to eclose, right? LOL

I've used the bag method twice for large numbers of Monarchs (8-10 per bag) with good success. However, during my recent batch, I did have several escapees, even with those black document clips. It really is important to fold the bag over at least twice and then clip it. I don't keep my leaves or branches in water, either. I just make sure I put fresh food in at least daily.


    Bookmark   September 14, 2013 at 9:19AM
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