Missouri Master Naturalists- Springfield Plateau Chapter

Thursday, July 18, 2019

Spined Assassin Bug


Little things count on a WOLF School field trip.  One of the students pointed out a tiny (3mm) speck crawling on my shirt.   A quick macro photograph let me share his find with the class, a first instar nymph of a spined assassin bug, Sinea diadema.

Assassin nymph on his arm - Kevin Firth
Assassin bugs are in the Reduviidae family along with ambush bugs
and the gear-backed wheel bug.  These are all ambush predators, attacking almost any insect they can find.  They tend to wait patiently on flowers such as goldenrods, then suddenly plunging their proboscis into the victim and injecting digestive juice.  Using external digestion, it then slurps up the liquid innards from its victim with nary a burp.

Spined assassin - note the proboscis tucked under its chin - Lisa I. CC

Stegosaurus armatus - Wikipedia

Adult assassin bugs have a prehistoric look like a downsized dinosaur.  This is especially true of the spined assassin.  It resembled a big headed Stegosaurus with a proboscis.  While the spines on the back may be defense against predators, spikes on the front legs and head may help them hold on to larger prey.
Spined assassin adult - Tom Murray
"This insect hides in plant foliage or on flowers, waiting for an insect to pass by it. The strong front legs grab the prey and a long fang at the mouth repeatedly stabs the insect to death with rapid piercing movements. If handled carelessly, this fang can prick human skin creating a mighty painful wound." Insectidentifidation.org
At this point I am going to hand you off the Bug Lady from the University of Wisconsin Milwaukee Field Station for more details in her usual gifted writing.  Enjoy!

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Bug Lady always comes up with interesting facts that otherwise escape me.  I am addicted to her Bug of the Week column and you may be too.