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Why do insects die so quickly when you trap them in a glass?

  1. Sep 4, 2017 #1
    When insects find their way into my home, I usually trap them in a glass & chuck 'em outside, opposed to squishing the poor buggers. However I sometimes forget, & when I return several hours later, to my dismay, they have croaked it. I don't understand. Shouldn't there be enough oxygen in a 500ml glass to keep a mosquito alive (for example) for way beyond several hours? I have observed this so many times. Not all of them die after a couple of hours, but I would say the majority do after 12 hours. What is killing these things? The only other things I can think of are heat, or even shock. However I live in a relatively cool climate (England), and don't leave them in direct sunlight.
  2. jcsd
  3. Sep 4, 2017 #2


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    Science Advisor

    Not enough information: What kind of insects/how many?
    Generally, this has not been my experience with most insects.

    Test hypotheses:
    • O2/CO2: Punch some small holes in your containers top, or some bigger ones which are plugged with cotton or something like that.
    • Lack of humidity: add a wet piece of cloth, paper towel, or a wet food like jello.
    • Providing a hiding place (under paper or leaves?) might overcome their being stressed.
  4. Sep 4, 2017 #3
    Thank you for your reply, BillTre.

    Usually I catch mosquitos, midges, & spiders around the house. I only put one insect in a glass, as the other one will usually fly out if I remove the lid.

    I was hoping some bio-major had a clear-cut answer. If not, then I will do some tests myself. Good suggestions, by the way. Humidity didn't even occur to me.
  5. Sep 5, 2017 #4

    jim mcnamara

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    Staff: Mentor

    There is something called sampling bias - or sampling error is another name.

    Remember that insects in general do one of these: (A) egg -> larvae -> metamorphosis -> adult, (B) egg -> nymph (several stages) -> adult
    Some things to consider:

    The free flying bugs we see, especially type A, are often very short lived as adults. Most species require very specific habitats. Also, many live less than one or two days as adults. Put them in a jar and they die the next day. Leave them outside and they die the next day anyway. So maybe the jar is always not a cause of mortality. Like @BillTre mentioned.

    When you capture bugs in a jar, you are getting a very very tiny sample of all of the bugs in your local area. A one acre field can contain as many as several hundred million insects. There are about 200 million inivididual insects on earth for each human.

    Your sample does not represent all of the bugs in your yard or house. So 'all bugs die in glass jars' may not be accurate in that sense. It may be that more slow moving species are easier to catch, and happen to be type A. And these guys are not larvae which usually outnumber adults for most species.

    Long ago I ran some bug traps in Peru. Light traps at night trapped so many bugs we could only run them for a few minutes before the collection bag (about 3 liters) was overflowing. A colleague of mine used bug bombs to collect insects in the Amazon basin. This was pre-1970. He put down a circular thin mesh mat around the base of a tree, fired off a bug pyrethrin(?) bomb, then watched insects rain down for 15 minutes. The mat was about 10m radius, and usually wound up with about a 5cm (2 inches) deep bug layer. Millions of insects. I do not think he ever counted them or would would still be doing the counts. He did weigh them, I think.

    The point is your sample of bugs in your jar does not really represent what you think it does.

    Example from Panama:
    Bug species in one acre (not individual bugs):

    San Lorenzo Forest - where the bug count above was taken:

    A field left fallow for a few years also has large insect populations.
  6. Sep 5, 2017 #5
    No! The Oxygen is not enough, try to use a semi-permeable material to close yo container.. environmental conditions and habitat might be the major factor in some animals..
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