Results from insect pathologist into Monarch deaths

  • Creator
  • #33529


    The results are back from the insect pathologist as follows:

    The dead caterpillar from PERSON A had a large bacterial infection. It also had some fungal hyphae (threads) but only in small numbers so I’m not sure that it would have been at a high enough level to cause death. I also can’t tell you whether both were there before death or whether they moved in after the caterpillar died. Bacteria in particular gets in very quickly once the caterpillar dies and can build up large numbers in a very short period of time.

    The two dead pupae (chrysalis) that come from PERSON B both had very high levels of bacteria (again possibly post-death as they stank of it). They also had huge infections of spores identical to Ophryocystis elektroscirrha. I did the “tape test” suggested by on the outside of the abdomen of one of the pupae, which confirms that it was on the outside. I know you said that the symptoms weren’t consistent with OE death, but the very high numbers of spores suggest that this could well have been the cause.

    Other than the above there were no signs of any other pathogen such as Nosema. There were also no signs of polyhedra in the cell nuclei or surroundings, and the caterpillar had little liquefaction, which pretty much rules out an NPV. It is possible that something much smaller has infected them, but as we can only go to 900x magnification with our equipment, anything smaller than NPV becomes difficult to detect by light microscopy.

    If it helps I can vouch for the use of diluted bleach solution for sterilising eggs and foliage. I have used 0.1% in the past for keeping disease away, although the monarch website recommends 10% (under “rearing monarchs”).

Viewing 11 replies - 1 through 11 (of 11 total)
  • Author
  • #33799


    Thanks Jacqui and Norm for your feedback.

    When we completed the survey at our butterfly meeting I did note that only two of seemed to have a major problem. Perhaps it was the drought and heat that caused the problems, as everything is going great at present in the butterfly house.

    We collected over 80 caterpillars in the last week and have managed to have a majority of these pupate successfully, so here is hoping.

    We did say to the group you will have losses in Mother Nature  and need to factor this in. We were just puzzled by the losses we were having. I’m still keeping a diary and noting everything down.

    We will never give up!! We love our butterflies far too much to be discouraged and lets see what next season brings.



    Agreed there are some unusually large losses with a couple of the groups, which is of course a concern.  Interesting that the pupae from one group recorded a very high count of Oe spores, where the larva from another group showed bacterial infection, so perhaps there was no common factor among the different groups but rather each had a differing problem.  Possibly the drought conditions may have been a contributing factor in compounded disease or feeding problems, but it may be impossible to pinpoint exactly the cause of the mortalities.  Jacqui has quoted a notable  fact  –  “when you have livestock, you’ll have deadstock”, and while we all want to rear our butterflies through without mishaps, nature has other ideas.  All this of course is not much help to those looking for answers, but don’t get discouraged and keep on raising the butterflies in the best conditions you can provide.



    Hello Char

    Thanks for this.

    I hope that Norm will post his thoughts on these numbers but if I’ve got these ratios right, these are my thoughts. I have ordered them in high numbers of mortality.

    Massey – 50:300, that’s 1 successful for each 6 that didn’t make it. 1:6

    Ranui – 30 to 30, 1:1

    Te Atatu South – 118:37 or 3 successes to 1 unsuccessful, 3:1

    Stillwater – 137:30 or 4.5:1

    Another factor which has bearing is years of experience and for someone with a history of six years, your numbers are alarming. However, people who are relatively new to it obviously will be less aware of the threats that butterflies are at risk and the mortality rate. One person who was new to it was mortified that one caterpillar had died… and I go back to the message from a farmer given to me years ago “when you have livestock, you’ll have dead stock”.

    So for those reasons, I don’t think the Te Atatu South and Stillwater results are of concern, but the Ranui case and your own would be something that would have been worth pursuing further.

    I do wish that we could pinpoint the problems that you were experiencing. I had expected that the panel at the conference would have had some ideas but in the end their suggestions didn’t throw any more light on things than we had suggested/discussed in the forum here already, or covered in basics in the Create Butterfly Habitat course.

    It is quite possible, of course, that it is a form of nosophobia or “medical student syndrome”.

    This is the phenomenon that occurs fairly regularly in med school students where they begin diagnosing their friends, family members, neighbors, cashiers, taxi drivers, pets, and themselves with whatever horrific illness they are currently studying. Twinge of stomach pain? Gastrointestinal bleed. Mild cough? Tuberculosis.

    A psychology student can fall prey to this “disease” as well. And I’m inclined to think it’s even easier to “diagnose” someone when you’re a psychology student. That girl in class who always has something to say just to hear herself talk? Histrionic personality disorder. That guy who just gave you a funny look in the hall? Paranoid schizophrenic. Any little behavior can be misconstrued as something it’s really not.

    (I got that myself 20-something years ago when I was working as secretary for a psychiatrist. Every letter I typed about someone’s symptoms, I thought to myself “OMG, I have that” or “I do that”. I had to give the job away. ROFL)

    Gillian and Kim’s issues seem to have been resolved or at least lessened. And good to hear that yours are doing well (in another thread). I hope that there are no further problems… until next time (of course).



    Sorry I’m late in posting up information. We’ve a rather busy few weeks since our meeting and been a way on holiday.

    We live in Massey and have been raising Monarchs for 6 years now:

    Successfully raised so far  – 50 Monarchs

    Unsuccessful ratio – 300, plants are self grown and some bought.

    Tagging in 2012 was 52 in March, 92 in March 2011 and this year has been 18 so far.

    G lives in Teatatu South, West Auckland and raising Monarchs for 18months now:

    Successfully raised so far  – 118 Monarchs

    Unsuccessful ratio – 37

    plants are self grown.

    Tagging in 2012 was 100 in March, March 2013 is only 46.

    J lives in Stillwater and been raising Monarchs for 18 months now:

    Successfully raised so far  – 137 Monarchs

    Unsuccessful ratio – 30

    plants are self grown.

    B lives in Ranui, West Auckland and been raising Monarchs for 2 years now:

    Successfully raised so far  – 30 Monarchs

    Unsuccessful ratio – 30

    plants are self grown and some bought.

    Hope this helps Jacqui.




    Yes I agree with Terry in that Norm did write a perfect summing up of the problems caused by overcrowding.  I think it would be great to cut and paste those two paragraphs and put them into the FAQs section under a new question  such as: how many caterpillars can my swan plant support?

    The reason for saying this is that it appears that the common issue for many who are new to breeding monarchs is running out of milkweed. If a guideline could be given as to how many caterpillars a plant of say 1 metre high can support, it might help people judge their food supplies more accurately. I know how easy it is to underestimate the amount of food even a small number of caterpillars can go through!!





    I can vouch for the bleach method of sterilising Butterfly eggs, I have found 10% solution for 15 minutes with Yellow Admiral eggs works well, However I cannot say this would be a safe dilution for Monarch eggs as I have never tried it with that species. Monarch eggs appear and probably are softer than Admiral eggs so I would urge anyone using bleach to start at a higher dilution and see what the results are before risking 10%. As most readers of the Monarch trust website will know I have been using a product called “Domestos Extended kill” which has other chemicals other than straight bleach but it still seems to work well.
    I was surprised when I first tried mist spaying my Urtica Dioica, Stinging Nettles with 10% Domestos expecting it to kill the plant and the larvae but incredibly it had no effect on the Nettles and although the larvae at first stretched out and appeared dead they came back to life and were ok in the long term. However, I also found it did not prevent the disease breaking out in the larvae at a later date probably because the organism was already in the gut and safe from the Bleach. The best method of disease prevention is don’t overstock and keep the cages or Butterfly House clean. In the event of a major outbreak sterilise the equipment and Butterfly House and then after a month or two start again with fresh plants and livestock
    Norm did a perfect summing up when he quite correctly pointed out that overcrowding and the stress it causes is normally the cause of these disease outbreaks and my Yellow Admiral project is living proof of this theory being true.



    It is estimated that only between 2 and 5 per cent of butterfly eggs will make it through to the adult butterfly in the wild, beause of the predators, diseases and conditions that take their toll on the eggs, caterpillars, and chrysalis.  Which is the way of nature and why butterflies lay so many eggs, so one cannot expect to rear all the eggs through to maturity without some falling by the wayside, unless one has clinical conditions and top quality healthy plants.  Monoculture in gardening is frought with its own problems, and raising large numbers of butterflies in a small area has similar problems.  Excess heat, cold, humidity and dampness can all affect both the plants caterpillars feed on, and the caterpillars themselves. 

    Overcrowding is one of the biggest causes of problems which  stress the caterpillars, and entomologists agree  that stress can trigger diseases in caterpillars.  Once a disease starts it is hard to control it without euthanasing the caterpillars and starting again. 

    So keeping realistic numbers of caterpillars relative to the number of plants available is the keynote, and each must decide for themselves the best system,whether it be culling the eggs, covering the plants with net to restrict more eggs being laid, or keeping the caterpillars on potted plants in a castle or indoors.

    A prominent international butterfly breeder remarked that it is not too important to define which bacteria or virus caterpillars die from, it just indicates the need to get things back to a healthy state again.  My thoughts are that with monarchs, Oe is one of the commonest sources of infection in Monarchs and can display a large variety of symptoms at all stages of development. 




    Hi Jacqui, thanks for posting that info. I’ve been waiting to hear how it went.

    I guess I’m one of those who gets upset when my pillars die! It’s my first season with them, so I guess it’s disappointing. Mind you, out of 24 pillars, I only have 6 left and one of those looks pretty slow and ill right now.

    I will just let them run their course, and try not to get too attached to them. Thanks! 🙂



    Definitely Charlotte – exchange of information is most worthwhile. What will be most helpful is knowing (roughly) how many years someone has been raising Monarchs, the ratio of unsuccessful to successful, and what the total number of successful (or unsuccessful) emergences – plus the area people are from. The latter to see if there’s any geographical pattern, but you would have picked up on this no doubt.

    The experience, total number and ratio is important as quite a few people who are new to raising Monarchs get upset when just one dies. They don’t appreciate how low the success rate is in the wild. On a butterfly farm, where everything is sterile and caterpillars are raised in their individual totes, the success is much higher. So experience and “size” of the population will help build up a better picture.




    Wow interesting feedback Jacqui.

    I actually think that next season we will sterilise all eggs before they hatch out. A lot more work but will definitely be worth it in the end.


    If its worth it I can place up the information we gained form our meeting on Saturday on everyone’s problems within the group.




Viewing 11 replies - 1 through 11 (of 11 total)

You must be logged in to reply to this topic.