30 June 2015

Assassin bug - updated


I was out in our garden yesterday collecting Monarch butterfly eggs (found twelve of them).  The photo above shows the surprise I found under one leaf.  I came back later after she had finished to get this photo of the cluster of eggs: (click both images for fullscreen)


She appears to me to be from the group of true "bugs" but I don't know her precise identity.  I suppose I could search on BugGuide, but instead I'll leave it open for the readership to ponder.  Some reader out there will be knowledgeable enough to offer a proper name that I can put in the title.* 

*solved by readers bucaneer, Shrike, and William D. Richards, who recognized it as an assassin bug:
The most common assassin bugs in our area are members of the Zelus genus... They are slender, long-legged bugs that are usually found on leaves and flowers, where they hunt by ambush. Length is 10-15 mm. Zelus species can fly and will if frightened, but they usually stay put and rely on their camouflage to hide them from both predators and their prey. They capture prey with their front legs, which are coated with sticky hairs.

Zelus eggs are laid on leaves in a small cluster. They have white caps on top. When they hatch, the nymphs disperse very quickly, as they will eat their siblings if given the chance... 
I have seen slightly different (more robust) assassin bugs in our garden holding dead butterflies and moths.  Didn't know they preyed on caterpillars, but I'm not surprised.

Update:  I monitored the eggs every time I went to the mailbox.   Nothing happened until yesterday (July 16 - 18 days after they were deposited), when I saw the underside of the leaf was just boiling with a mass of baby assassins:



The photo quality is marginal, but o.k. for documentary if not artistic purposes.  I don't know why some of the nymphs are milky white while others are more translucent - whether this is a true dimorphism or whether some are older and their exoskeletons are maturing.

10 comments:

  1. It is Zelus sp. (probably Z. luridus), a predatory bug.

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    1. Looks a bit more like the pictures I can find online of Z. renardii, what with the points on the sides of the pronotum (exoskeletal plate behind the head and protecting the wing joint). (Also thank you TYWKIWDBI, I am now several hundred percent more educated about insect anatomy than I was ten minutes ago.) The images I can find of Z. luridus all look pretty thin.

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  2. Bucaneer beat me to it: she's an assassin bug.

    Those mouth parts ain't for suckin' on plants, I assure you. Her offspring will be looking for caterpillars to feast on when they hatch.

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  3. So now you have a moral dilemma -- do you destroy her eggs to try to save caterpillars or do you let nature take its course?

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    1. I don't intentionally destroy any creatures except mosquitoes. This servesas an example of why my wife and I harvest butterfly eggs we find in the garden and move them to our screen porch, where they can mature away from predatory wasps, spiders, ants, birds (and now bugs).

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    2. I know you wouldn't kill anything intentionally. Speaking of mosquitoes, why do you think God had Noah take a pair of them on the Ark? Seems that would have been the perfect time to eradicate the little suckers!

      Your post has reminded me to go look for butterfly eggs on the milkweed I planted at your behest last summer. This summer it is really thriving, but much taller than I thought milkweed would grow. It's taller than I am. Thank you for providing a spot that is sometimes funny, but always thought-provoking. I look forward to reading your posts every day.

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  4. can you post some photos of the monarch eggs? in all their royal splendor, of course! :-)

    p.s. b. eggs are really small, so the h-e-heck do you even find them?

    p.p.s how long did you spend looking for them before you found them?

    I-)

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    1. http://tywkiwdbi.blogspot.com/2012/05/first-monarch-eggs-of-year.html

      http://tywkiwdbi.blogspot.com/2013/06/monarch-eggs-on-milkweed.html

      http://tywkiwdbi.blogspot.com/2013/08/monarch-eggs-on-milkweed-pods.html

      To find those dozen eggs I looked under the leaves of about 40 milkweed plants in our gardens; it took about 15-20 minutes, but I was moving quickly because of the mosquitoes.

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    2. thanks, butterfly dude! :-) i hope you post a series of photos showing the eggs growing, and growing, and growing.

      I-)

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  5. Be careful, these bugs are the main vector for Chagas disease, which is fatal for humans and pets.

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