Assassins are on the Loose!

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It’s common for people to call all insects bugs.  However, entomologists reserve the bug name for a specific group of insects that belong to the suborder Heteroptera (order Hemiptera).  To emphasize the point, entomologists refer to these heteropteran insects as the true bugs which may imply we consider all other insects to be false bugs but that’s not true.


Insects that belong to the heteropteran family Reduviidae are collectively known as Assassin Bugs.  The family includes over 190 species in North America and they are all meat-eaters.  The common name for the family clearly describes how these predatory stealthy hunters make a living.


Assassin Bug


Family members sport two features that support their predatory lifestyle.  They have raptorial front legs designed for grabbing and holding prey.  Their piercing-sucking mouthparts are called a beak.  It swings into action (literally) to inject paralyzing and pre-digestive enzymes into prey which is most often another insect.  They then suck the essence-of-insect from their hapless victims.


Wheel Bug


Assassin bugs develop from eggs to adults through incomplete metamorphosis.  I've never liked this term because it sounds like something horrible can go wrong during development like only popping out legs on one side of their bodies so they run around in circles (just kidding).


It actually means they pass through three developmental stages:  eggs, nymphs, and adults.  This is in contrast with insects such as butterflies that develop from eggs to adults through complete metamorphosis where a complete change occurs during the pupal (= chrysalis) stage.


The nymphs of many insects with incomplete metamorphosis like grasshoppers (order Orthoptera) look like a miniature version of the adults.  However, assassin bug nymphs commonly look nothing like adults.


Wheel Bug


In fact, many types of assassin bug nymphs are commonly mistaken for spiders.  A good example is the nymphs of our native Wheel Bug (Arilus cristatus).  Of course, spiders have eight legs while wheel bug nymphs have six legs.


Wheel Bug




Wheel of Misfortune

Wheel bug nymphs are one of the most common types of assassin bug nymphs currently patrolling trees and shrubs in Ohio.  The nymphs hold their curved abdomens upright as they parade around on their long, spindly, spider-like legs … unless three on one side fail to develop and they run around in circles which is why they're called wheel bugs (just kidding!).


Wheel Bug


Wheel Bug


Wheel Bug


Wheel Bug


The adults are called wheel bugs because of a peculiar feature that rises from the top of the bug's thorax.  The structure looks like half of a cogwheel, with the gear teeth clearly visible.  Wheel bugs are big, measuring over 1 1/4" long, and their color varies from light gray to bluish-gray to grayish-brown.  They will appear on the tree scene later this season in Ohio.


Wheel Bug


Caterpillars and sawfly larvae are favored table fare of these voracious predators; however, they will not turn their beaks up at other arthropod meat morsels.  Indeed, they will even nail the probing fingers of uniformed gardeners!


While these are beneficial insects, they should not be handled.  All members of the family are capable of delivering a painful bite to people.  The pain of a bug bite has been described as being equal to or more powerful than a hornet sting, and the wound may take over a week to heal.  It is best to appreciate these beneficial insects from afar.



A Bug-Induced Panic

Wheel bugs were at the center of a bug hysteria that swept through Ohio as well as several other states in 2015.  The panic was induced through a series of unfortunate events starting with wheel bugs being misidentified as kissing bugs (Triatoma spp., family Reduviidae).


The name "kissing bug" sounds non-threatening until you learn that several species of bugs belonging to the genus Triatoma tend to bite near a person's mouth like they're kissing a person (eww!).  These "triatomine bugs" get away with their cheeky behavior by biting people while they sleep.


The bites are usually painless but may lead to a serious disease if the bugs are harboring the protozoan Trypanosoma cruzi in their gut.  The bugs don't inject the protozoan when they bite; they release it from their other end when they defecate, an unpleasant thought.  Infection occurs if the protozoan is accidentally rubbed into the bug's feeding wounds or onto mucous membranes such as nasal passages.  The resulting Chagas disease is nothing to sneeze at; it can be deadly.


Thankfully, the kissing bug / Chagas disease connection only occurs in Central and South America with some rare occurrences in Texas.  Conditions don't support the same relationship here in Ohio.


Even though wheel bugs and kissing bugs belong to the same family, their lifestyles are completely different.  Wheel bugs suck insect juice; kissing bugs suck animal blood.


However, with their long spindly legs, large bodies, narrow heads with beady eyes, wheel bugs do share family features with their kissing cousins.  Consequently, pictures of wheel bugs started showing up on the Web identified as kissing bugs.  That spawned an alarm that rippled through several media outlets.


Wheel Bug


There is a kissing bug called the Bloodsucking Conenose (Triatoma sanguisuga) that may be found in the northern U.S. including Ohio.  Although it has a scary-sounding common name, the conenose is very rare in Ohio and it doesn't acquire and spread the protozoan responsible for Chagas disease.  This means we can sleep soundly without worrying about bugs pooping on our faces. 


Kissing Bug