Tonight at around 10 PM, we were in for a gruesome sight when we saw one of our sixth instar Mediterranean Katydids (Phaneroptera nana) cannibalizing a molting fifth instar! We have always had issues in the past with mild cannibalism in katydids when they are overcrowded, with both Mediterranean Katydids (Phaneroptera nana) and Mexican Bush Katydids (Scudderia mexicana), and it is a pretty disgusting sight. Usually, it isn't really too bad -- just the occasional gnawing of the tips of limbs and wings. We even once had a Mexican Bush Katydid cannibalism a fallen roommate back on 5/27 this year. But today, we had the chance of catching red-handed one of our Mediterraneans eating its comrade live in cold-blood. A ton of interest has been sparked by the cannibalistic tendencies of some animals and in most cases, the verdict has been that cannibalism increases fitness by directly advantaging the perpetrator(s) who reap additional nutrients from the cannibalized. There is plenty of scientific literature available on this behavior, even in some insects such as the infamous praying mantis which makes sense since they are strictly carnivorous anyway. But much less has been studied about cannibalism in Orthoptera, most of which are normally herbivores. One species that has been studied extensively is a flightless katydid called the Mormon Cricket (Anabrus simplex). Basically, these katydids march on their feet in huge swarms and devour any vegetation they come across, similar to the destructive nature of locust swarms. But should any of its members become weak and stop marching with the rest of the group, they are immediately pounced on by nearby crickets and cannibalized. The long-standing hypothesis seems to be that running the risk of being cannibalized by sticking with the gang is better than going solo where the chance of regular predation is much higher. (Read Katydids and Bush-Crickets: Reproductive Behavior and Evolution of the Tettigoniidae by Darryl T. Gwynne for more information.) What we have seen in our katydids is probably a similar principle. Like Mormon Crickets, cannibalism in Mediterranean katydids is clearly highly density dependent; the more individuals there are, the higher the chance of cannibalism. For example, Mormon Crickets would probably rarely cannibalize if they weren't in a swam and living solitary and our Mediterranean Katydids would probably also rarely cannibalize if they weren't so overcrowded (We are keeping over 40 of them in one little tank right now!). They just wouldn't have the chance to since it's not like they are actively searching for others to attack like a true predator. Furthermore, the taking advantage of weaker members in the Mormon Crickets is a similar idea to our katydids taking advantage of molting individuals who are also weak and unable to defend themselves. After all, most Orthopterans (especially Tettigoniidae) are opportunistic omnivores that will scavenge for dying or dead invertebrates in the wild. In any case, the damage has been done already and we do not have the space or time to completely prevent overcrowding and/or cannibalism by housing each individual separately. We have caught well over 50 Mediterranean Katydids this year and only 42 now remain in the tank. Though some may have simply escaped while changing food, many of them are presumably cannibalized. There are few thing that would make us think otherwise after seeing what happened tonight! At least we hope that those that have participated in the cannibalism gain some benefit out of it and help us produce some mighty fine eggs when we attempt to breed them later. - Brian
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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)
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![]() ![]() 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 |