Small black dots on caterpillars.

    Hello,


    For now 4 species that I have reared has developed black dots as they reached the middle of their final instar.
    These have not caused any deaths in my rearings, but they are annoying when it comes to takkng picture of them.
    It's not a parasite, and it doesn't affect the moths as the moths that emerged last time, with the same problem (A. Ningpoana fed on Juglans) did not change from healthy specimens (males ~11cm, females ~14cm). I did only have a single crippled specimen over 13 cocoons.
    It happened with this previously mentioned species, but also with Saturnia pyri on Fraxinus, Sphinx ligustri and Rothschildia lebeau on Ligustrum, and also Actias luna on Juglans. Last year I did not have this problem with my first luna rearing, but this year I had.
    People I sent eggs to doesn't seem to have that problem, I recieved eggs of ningpoana from another brood to pair them with my brood, both broods had the same problem, however, the guy who sent me the eggs did not have that problem... And still doesn't


    I am thinking that maybe it is due to an excessive pollution, did anyone have this problem? I am searching for answers :winking_face:


    Thanks a lot if you try to help me!


    Thomas.

    • We specialise in rare and common butterflies from the Neotropical (Central/South America, Caribbean Islands) and Holarctic regions (North America, Europe, Asia).
    ANZEIGE

    Hello Thomas,


    I also know this problem and I think it is a fungal infection on the "skin" - also from my experience it does not usually lead to serious health problems, but if it occurs too strongly it may have "recognizable" effects on the caterpillars / pupae (if it be the same with me, it can also affect the pupae and the black spots can sometimes be bigger and if they are on the wing sheaths for example, the hatching moth has pigmentation defects at these spots - that's my observation).
    It can affect all caterpillars in a breed or only a part and other species seem totally insensitive to it (especially native species such as Geometridae and so on).
    I suspect it is actually caused/promoted by too humid breeding conditions.


    best regards
    Sascha

    Hello Thomas,


    This issue has been also already discussed here, but I can not find the thread anymore (from there I think I have the thought with the fungal infection).
    I suspect most susceptible (perhaps because of their relatively soft skin) are Saturniidae caterpillars, Sphingidae caterpillars, I think are much less sensitive (but if you have it in a running breed, the caterpillars naturally infect each other and it also gets caterpillars which otherwise are actually less affected are).
    I also suspect that it is very common and most breeders know it, because when you look at caterpillar photos of a species on the web, there are also photos with caterpillars that have these black spots (if not many people found it unfotogenic, there are certainly many more photos of such caterpillars :winking_face: ).
    But information about what it is exactly I have not found any.


    Here are a few examples of the image search of Antheraea polyphemus:


    - antheraea polyphemus - Bing images
    - antheraea polyphemus - Bing images
    - antheraea polyphemus - Bing images
    - antheraea polyphemus - Bing images


    Best regards
    Sascha

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