Sunday, August 12, 2012

Adventures in Spider Misidentification: Oviposition by spider

Mystery spider and desperate midge
Ted MacRae recently posted a picture of a tropical orb weaver that is enough to scare the bejesus out of any self-respecting arachnophobe. Did something similar happen here? I don't know. Other than knowing this is a male spider, by its palps, and a female midge, by her eggs, this interaction is a mystery to me. Did the spider squeeze its lunch too hard? Or is induced oviposition a viable strategy for saving a few offspring when captured by a predator? Who knows? Things are not always what they seem.
Pretty bee-friendly wildflower or noxious invasive weed?
For example this pretty 'wildflower' I discovered last weekend hosting a Tricoloured Bumble Bee turns out to be the insidious Common Tansy (Tanacetum vulgare) an introduced plant that is toxic to livestock that eat it. It's toxic to us too, but the chances of ingesting it aren't high unless you believe the Greek myth about it being an ingredient in the potion that turned Gandymede, a shepherd who had the misfortune to attract the attentions of Zeus, immortal. Still, some might be tempted, but you are more likely to go into spasms, foam at the mouth, and join the midge above in the hereafter, than achieve immortality. Tansy has had numerous external uses, for example as an insect-repellent, for embalming, to whiten the skin, and "to encourage the fertility of the sexual organs and to relieve sprains and headaches" (see previous link). However, for me it means spending Sunday afternoon coming into compliance with the weed act and removing it from my property.


  1. Interesting, and induced oviposition could be the explanation. I once swatted a tachinid/sarcophagid fly - hard enough to stun it but not kill it, and within a few seconds a couple dozen 1st instar maggots started crawling out of its abdomen. (This happened when I was a kid - really left an impression on me!)

  2. Interesting spider find.

    Last week I was surprised that the ponds at Edmonton's Jan Janzen Nature Centre were surrounded with large clumps of tansy and thistle. This week the were all cut down - and the stems and seed heads left scattered around.
    I look forward to seeing how far their weed crop will expand next year...