Our luna moth (Actias luna) larvae have all finished spinning cocoons. Since all the larvae have spun up, we went ahead and collected all the cocoons from the tubs and ripped off all the leaves. There are just 19 cocoons total which is very few for how many we started with, but we're not too worried though as it is not the most valuable species. While rearing the larvae, we had put them in an opaque tub starting in the fourth instar which blocked out light when closed, allowing us to limit the light to only a few hours a day. Thus, we expected that all the cocoons would diapause and be made of tough, brown silk than the thin beige of the normal, non-diapausing ones. However, after inspecting all the cocoons, we saw that there was a very large variation in silk color, with some being extremely dark brown, others being almost white, and many being an intermediate orange-brown. The dark brown and probably also orange-brown ones should be in diapause, but we can't be sure about the beige ones. They look just like the spring cocoons that did not diapause, but perhaps the silk just hasn't hardened and tanned yet. Some other interesting things about this rearing's cocoons are that one of the cocoons is extremely large, thin, and baggy, rather than the normal round and compact. It sort of resembles the baggy form of Hyalophora cecropia cocoons, though this form is not supposed to exist in luna. Perhaps something about the way the available attachment points were arranged while the prepupa was spinning caused it to produce such an odd cocoon. Other unusual cocoons were two pairs of fused cocoons due to the larvae spinning right next to each other. We were able to split them apart without damaging them with some difficulty. Anyway, on to the mass data. After collecting the cocoons, we weighed and recorded their masses and calculated some summary statistics, shown below: Summary Statistics for Actias luna Cocoon Mass (Summer 2017): Mean Std Dev Median Min Max N 2.750 0.541 2.68 1.98 3.86 19 For comparison, we pulled up the spring stats as well: Summary Statistics for Actias luna Cocoon Mass (Spring 2017): Mean Std Dev Median Min Max N 3.525 0.411 3.4 3.0 4.2 12 What's the first thing we noticed? That's right - a ridiculously lower summer cocoon mass compared to spring. Sample size is small, but the difference is still quite extreme. A two-sample t-test for the difference of means between spring and summer cocoon mass also supports that the difference is statistically significant (t = 4.2357; df = 29; p=0.0002). Right now the first explanation to come to mind is simply the severe overcrowding the summer larvae experienced in later instars. But really, it wasn't too much worse by the fifth instar compared to in the spring rearing. Food quality should have been about the same, so the only other difference was the temperature and humidity. The spring larvae were incubated at constant 27°C and high humidity during the first three to four instars while the summer larvae were at room temperature their entire lives. However, this seems to be a contradictory factor, since from what we've seen, the high constant temperature of the incubator tends to speed larval growth drastically at the cost of size. Plus, by the fifth instar - the critical growing period, both spring and summer larvae were at room temperature. The only other factor that could have played a significant role in size reduction was inbreeding. The summer larvae were inbred offspring of the outbred spring larvae. It is hard to say how exactly the recessive gene stacking affects the larvae, but from what we suspect and what some other hobbyists claim based on observation is that inbreeding tends to reduces size. We only inbred for one generation, but perhaps that was enough to cause this extreme drop in size. ![]() Authors Alan Liang
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Timeline 2012–2017
Albany, California This timeline is a series of daily posts recording our observations on and experiences with various insects in Albany California and surrounding areas, from 2012-2017. Since we did not publish this site until 2016, posts before that were constructed retroactively. Starting in August 2017, we moved to Ithaca, New York; posts from there on can be viewed at Timeline 2017-present: Ithaca, New York. Archives (1,011)
August 2017 (49) July 2017 (121) June 2017 (79) May 2017 (77) April 2017 (91) March 2017 (35) February 2017 (12) January 2017 (10) December 2016 (12) November 2016 (26) October 2016 (49) September 2016 (84) August 2016 (94) July 2016 (99) June 2016 (53) May 2016 (21) April 2016 (4) January 2016 (1) August 2015 (3) July 2015 (3) June 2015 (2) June 2014 (3) May 2014 (1) April 2014 (3) March 2014 (3) December 2013 (2) November 2013 (2) October 2013 (5) September 2013 (11) August 2013 (15) July 2013 (9) June 2013 (5) May 2013 (4) April 2013 (3) March 2013 (2) February 2013 (3) January 2013 (2) December 2012 (2) November 2012 (1) October 2012 (2) September 2012 (2) August 2012 (5) July 2012 (1) June 2012 (1) Authors
![]() ![]() Full Species List (Alphabetical by scientific name) Note: - Not every species we encounter is necessarily presented on this site, rather a selection of those that were of particular interest to us and that we felt were worth documenting. - We can't guarantee that all species have been identified accurately, particularly taxa we are not as familiar with. Lepidoptera Actias luna Adelpha californica Agraulis vanillae Allancastria cerisyi Antheraea mylitta Antheraea polyphemus Anthocharis sara Argema mimosae Attacus atlas Battus philenor hirsuta Bombyx mori Caligo atreus Callosamia promethea Coenonympha tullia california Citheronia regalis Cricula trifenestrata Danaus plexippus Eacles imperialis Erynnis tristis Estigmene acrea Eumorpha achemon Eupackardia calleta Furcula cinereoides Heliconius erato Heliconius hecale Heliconius sapho Heliconius sara Hyalophora cecropia Hyalophora columbia Hyalophora euryalus Hylephila phyleus Hyles lineata Junonia coenia Langia zenzeroides formosana Lophocampa maculata Manduca sexta Morpho peleides Nymphalis antiopa Orgyia vetusta Orthosia hibisci quenquefasciata Pachysphinx modesta Papilio cresphontes Papilio eurymedon Papilio glaucus Papilio machaon oregonius Papilio multicaudata Papilio polyxenes asterius Papilio rumiko Papilio rutulus Papilio zelicaon Phyciodes mylitta Phyciodes pulchella Pieris rapae Plejebus acmon Poanes melane Polites sabuleti Polygonia satyrus Pyrgus communis Rothschildia jacobaeae Samia cynthia advena Samia ricini Smerinthus cerisyi Smerinthus ophthalmica Strymon melinus Trichoplusia ni Uresephita reversalis Vanessa annabella Vanessa atalanta Vanessa cardui Unidentified Lepidoptera Hybrids Papilio glaucus × Papilio rutulus Papilio polyxenes asterius × Papilio zelicaon Orthoptera Melanoplus devastator Phaneroptera nana Pristoceuthophilus pacificus Scudderia mexicana Trimerotropis pallidipennis Phasmatodea Carausius morosus Phyllium giganteum Mantodea Mantis religiosa Phyllocrania paradoxa Hymenoptera Apis mellifera Bombus vosnesenskii Brachymeria ovata Linepithema humile Pediobius sp. Polistes dominula Xylocopa varipuncta Unidentified Diptera Lucilia sericata Unidentified Hemiptera Brochymena sp. Leptoglossus sp. Nezara viridula Odonata Argia vivida Libellula croceipennis Coleoptera Coccinella septempunctata Cycloneda polita Diabrotica undecimpunctata Hippodamia convergens Araneae (Class: Arachnida) Araneus diadematus Phidippus johnsoni |