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What do assassin bugs do?

What do assassin bugs do?

Assassin bugs are fascinating insects that have some unique behaviors and abilities. In this article, we’ll explore what exactly assassin bugs do and why they behave the way they do.

What are assassin bugs?

Assassin bugs, also known as kissing bugs, are a large family of true bugs that all share some common features:

  • They have a narrow head that extends forward into a distinct “neck”
  • They have a curved, elongated mouthpart called a rostrum that they use to stab and suck fluids from their prey
  • They are ambush predators that lie in wait for victims and stalk them
  • They inject immobilizing and liquefying toxins into their prey
  • There are over 7,000 species found worldwide

Some of the most common assassin bug species kept as pets or found in gardens include wheel bugs, masked hunters, and kissless bugs. Assassin bugs come in a huge array of colors and patterns to camouflage themselves while hunting.

What do assassin bugs eat?

Assassin bugs are carnivores that prey on a wide variety of small animals. The most common prey includes:

  • Other insects and arachnids
  • Caterpillars, maggots, and other larval forms
  • Small worms
  • Lizards and frogs
  • Rodents and birds (in the case of the largest assassin bug species)

They use their long rostrum to stab their prey and inject digestive fluids that break down the prey’s tissues. Then they suck out the liquefied remains of their meal.

How do assassin bugs hunt?

Assassin bugs are ambush predators that use clever strategies to hunt down prey:

  • They hide in wait in flowers, leaf litter, bark, or other spots their prey will pass by
  • Some species dig pits in soil or sand to conceal themselves even more
  • They often use their colors and patterns as camouflage to avoid being detected
  • They patiently watch for passing prey using their large, segmented eyes
  • Once prey gets close, they stealthily stalk it or pounce quickly to grab it
  • They pierce the prey with their rostrum and inject paralyzing toxins
  • The toxins immobilize and start digesting the prey so the assassin bug can slurp up its liquefied remains

Different assassin bug species may vary in their preferred type of prey and exact hunting strategy. But most rely on stealth, patience, and their paralyzing bite to capture unsuspecting meals.

Why do assassin bugs “kiss” their prey?

Some assassin bug species like the masked hunter have a habit of pressing their cylindrical mouthparts against the skin of larger prey animals or humans after capture. This bizarre “kissing” behavior has a scientific explanation:

  • The rostrum likely stimulates nerve centers near the lips, nose, and eyes of prey in search of the best injection point.
  • In humans, kissing around the mouth area seems to allow the bug to determine if the skin is thin enough there to efficiently penetrate and inject venom.
  • The toxin proteins need to be injected near mucous membranes or thin vascularized areas for fast immobilization.
  • “Kissing” lets the assassin bug pinpoint the optimal toxin injection site to take down prey quickly.

So while unnerving, the kissing behavior is simply the assassin bug exploring the prey for vulnerable toxin injection points as part of its hunting strategy.

Are assassin bugs dangerous?

Most assassin bug species pose little threat to humans. Only around a dozen species (mostly in the Triatoma genus) are known to bite humans and feed on blood:

Assassin Bug Species Geographic Range
Triatoma protracta Western North America
Triatoma rubida Southwestern US
Triatoma rubrofasciata Subtropics worldwide
Triatoma infestans Central and South America
Triatoma dimidiata Central America, Colombia, Ecuador

These “kissing bugs” can transmit a parasitic disease called Chagas disease to humans by defecating near the bite wound. But overall, very few assassin bug species actively seek out humans, and most bites result in just mild skin irritation and itching.

Why do assassin bugs play dead?

Many assassin bugs exhibit a behavior called thanatosis or tonic immobility when threatened. Thanatosis involves:

  • The bug suddenly going still and dropping to the ground.
  • The limbs and antennae tightly hugging the body.
  • No visible movement of any kind.
  • This state being maintained for minutes to hours if left alone.

Playing dead in this way is thought to help assassin bugs survive predator attacks in a few key ways:

  • It startles a predator and interrupts its attack sequence.
  • The bug resembles an inedible object rather than prey.
  • It helps camouflage the bug against the background.
  • The predator may lose interest allowing the bug to escape later.

So for assassin bugs, thanatosis is an important last ditch self-defense mechanism when they can’t rely on their hunting skills to save them.

How do assassin bugs reproduce?

Assassin bugs display a range of interesting reproductive behaviors:

  • Males attract females by making vibrational calls by stridulating their body or beating their wings.
  • Mating rituals involve elaborate gestures like the male drumming the female’s back with his antennae.
  • Females lay clusters of eggs (up to 150) on plants, in the soil, or mudnests.
  • Some species exhibit extensive maternal care of eggs and young nymphs.
  • They go through incomplete metamorphosis with nymphs molting up to 8 times.
  • Total life cycle ranges from a few weeks to a couple years depending on species.

This diversity of reproductive strategies helps assassin bugs thrive in a wide range of environments and niches around the world.

How do assassin bugs defend themselves?

Though assassin bugs are predators, they still have to watch out for becoming prey themselves. So they have some key defensive adaptations:

  • Their tough exoskeleton provides armor against attacks.
  • Chemical secretions from scent glands deter predators.
  • Warning coloration with bright reds, oranges, and yellows camouflage some species.
  • Thanatosis or playing dead (as described earlier).
  • Their spit contains toxic components that can irritate skin and mucous membranes.
  • Some species can deliver a painful bite if threatened.

These defenses allow assassin bugs to hold their own against the frogs, birds, and spiders that see them as potential prey.


Assassin bugs have evolved a fascinating array of behaviors and adaptations that make them successful predators. Their stealthy hunting skills, paralyzing venom, bizarre “kissing” behavior, dramatic threat displays, and unique reproductive habits reveal the ingenuity of their biology.

While a small number of assassin bug species can pose disease risks and bite humans, most focus their behaviors on taking down other insects and small prey. Their specialized role as ambush hunters makes assassin bugs an important part of ecosystems worldwide.