Asked on Aug 9, 2019

What pest can be eating/infecting my monarch caterpillars?

Penne JohnsonMaura WhiteSharon


Updating you on my not to successful as yet trying to care for Monarch cats. Out of 19 I have one that made her chrysallis this a.m. when I turned my back of course. LOLI change their jars every morning and if they need more fresh leaves I add them in the afternoon. I had one that made her J and then never seemed to make a good J she had beenalive for 3 days including today. When I decided to dispose of her, I noticed a yellow worm likebody like that of rolly polly bug alive in her cage. Never noticed it as I checked on her constantly during the past 3 days. This one was alive, I had another cat that maybe 1 3/4" longthat had died and when I emptied her jar which I also had cleaned and gave new leave to yesterday there was another one of these that was dead in the jar. I wash my leaves prior to putting them in the jars to make sure there are no aphids on themand have no idea where these two things came from but obviously they kill the Cats. The oneI just found I noticed that the Cat had glued itself to the side of the jar since a.m. today andwas not mature enough to become a butterfly. Its a puzzle to me as to where they come fromand what they might be. Obviously harmful to the cats.I have 5 babies growing in jars that I took in as eggs on leaves, and I have 4 more eggs. I amwatching them ever so closely to make sure that these critters whatever they are aren't inthere. I am wondering if they may have been ingested by the cats maybe in their 1" size aseggs on leaves prior to my seeing and bringing them in to place in jars. AND are they possiblycoming from the frass. Whatever they are they grow much faster than the cats do. The one That made the chrysallis this a.m. I am hoping will be healthy. Thanks for responses.

4 answers
  • Sharon
    on Aug 10, 2019

    More likely a wasp larvae laid in the Cat to pupate.

  • Penne Johnson
    on Aug 10, 2019

    wow never thought of a wasp. Haven't seen any on my patio but do see lots of bees. As I said

    here in Calif. we have had some kind of what they feel is a certain fly virus that is getting our

    Monarchs. I lost two more yesterday that just died and they were larger ones. My babies from

    eggs seem to be doing good tho. Sure hope so. I have had so many beautiful Monarchs flying

    onto my patio and am sure next year will have them again. We also wonder if it could be the

    Mweed. Two of mine grew wild and two I bought at nursery. One H Depot the other at neighbor

    hood B&B. Thanks so much for your response Sharon. So far I have 4 eggs I'm watching. LOL

    That is how I got the 5 that are now growing. Online said that is the safest way to get healthy

    cats that hopefully aren't damaged by what ever. LOL Thanks again.

  • Maura White
    on Aug 11, 2019

    interesting - I collect monarch catepillars each year myself and have not experienced this. I've had a few die on me over the years, but not like the caterpiller epidemic you are seeing. very weird that the poor little catepillars are getting a parasite. HOpefully the eggs won't be infected.

  • Penne Johnson
    on Aug 11, 2019

    Thanks Maura. I as well am hoping. Right now I have 7 cats very small that I got from the eggs

    I put in a small lid on a wet leaf, and now I have 6 more. Everytime I go out side to cut a leaf

    which I am almost totally out of I find another egg and just can't destroy it. I am hoping beyond

    all else that the little on I hatched will be o.k. I have one near to making a chrysallis and two

    more that are about 1 1/2" long so am hoping they all live. So far I lost one that was in her J

    and 3 more that were sizes between the one almost ready and the next two down. If any of these ones die I will know that something got to them on the plants outside. The two that died

    that had the yellow something that grew after they were of good size (the cats) someone said

    probably that it was a wasp larva that had been injected in them and I guess they came out

    in their Frass which isn't something I want to see again. YUKKKK

    Thanks for responding.

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