Cockroaches have multi-purpose antennae. These antennas are used to move around, sense changes in humidity levels, and even pick up scent trails.
Most cockroaches are nocturnal and they need antennae to understand the surrounding environment.
Antennae are so important that species such as the American cockroach have been shown to regularly groom them. This shows the importance of these long flexible body parts.
Cockroach antennae have a multi-purpose role combining multiple senses. Antennae are primarily used for their tactical sense. Other purposes for cockroach antennae include olfactory, gustatory, thermal, and humidity perception.
Cockroaches depend on antennae for almost all actions. They can also lose antennae from predation.
However, cockroaches can also regrow antennae partially or completely within a few molts.
Cockroach antennae anatomy
Cockroach antennae are comprised of movable joints and long flexible segments. Apart from these, cockroach antennae also come with short
They are comprised of the following parts.
Scape – (closest segment to the head)
Pedicel – (mid-segment between the scape and flagellum)
Flagellum (long distal segment)
Hair sensillum – mechanoreceptor and chemoreceptor hairs on the flagellum
Campaniform sensilla – hairless mechanoreceptors on the pedicel and flagellum
Chordotonal sensilla – sensory units inside the pedicel
Hair plates – mechanosensory hairs at the base of the antennae
5 Uses of Cockroach Antennae
1. Cockroaches use antennae for movement
Poor vision is coupled with tactile antennae capacity to allow cockroaches to sense nearby objects. This involves following along objects such as walls and avoiding collision with other objects.
Moving along walls and edges
The tactile capacity of the antennae allows cockroaches to move along quicker. While not blind, cockroaches don’t have very good vision.
Cockroaches also rely on the tactile capacity of antennae to stay close to walls. This is a habit known as thigmotaxis.
The process involves having cockroaches following walls or edges, particularly when fearful.
Research shows antennae help cockroaches avoid colliding with walls under this habit.
Antennae are generally used to avoid objects when moving around. Cockroaches move quickly (at speeds of around 3 miles per hour) and need to be careful not to bump into objects given they don’t have excellent vision.
The way antennae hit objects tells cockroaches if the object needs to be avoided or climbed.
Air pressure, humidity, and temperature detection through antennae
Cockroaches depend on the right temperature and humidity. These are all indicators antennae is used to determine.
Cockroaches rely on thermoreceptors in their antennae to distinguish temperature changes. These thermoreceptors are used to stay clear of extreme temperatures, an essential survival skill.
Cockroaches prefer high humidity environments. Heat and humidity are preferred and antennae guide cockroaches to the kitchen or to the bathroom where these conditions are constant.
2. Antennae perceive barometric pressure changes
Barometric pressure changes indicate weather changes. Heavy rain can be fatal to cockroaches. This is why they rely on antennae receptors to sense changes in barometric pressure and seek shelter as needed.
Receptors in the antennae allow cockroaches to sense changes in air pressure and act quickly to seek shelter.
3. Vibrations are detected by cockroach antennae
Receptors in the antennae are essential in cockroach defense. Cockroaches sense nearby vibrations through antennae.
Detecting vibrations helps cockroaches sense whenever a predator or a perceived potential threat is getting closer.
The ability of cockroaches to detect vibrations also acts as a preventive measure to run away in case of falling objects.
They sense vibrations on terrains with mulch, leaves, or sand.
4. Cockroaches pick up odors by using antennae
Receptors in the antennae help cockroaches find food sources. Odors are picked up by antennae but different bug species do this in different ways.
Some bugs move upwind following food odor sources while other species move downwind.
The sense of smell is also associated with a defensive mechanism as cockroaches can smell approaching predators.
The sense of smell guides cockroaches to food and it also warns them of the presence of predators such as beetles and spiders.
Cockroaches run away when they sense nearby predators.
5. Antennae are used in cockroach mating
Male cockroaches pick up mating odors released by female cockroaches with olfactory sensors in antennae.
Females release pheromones which the antennae of male cockroaches pick up as mating signals.
It’s believed these signals are congruent with the nocturnal mating of cockroaches which need to guide themselves by odors in low light conditions.
These pheromones have a considerable influence on the male’s desire to mate, even when released in very small amounts.
What happens if a cockroach loses its antennae?
Cockroaches largely depend on their antennae. But injured or removed antennae is not the immediate end for a cockroach.
Antennae can regrow either partially or fully during the next few molts.
In the meantime, cockroaches have to adapt how they move and how they sense the world around them.
This is a time when most cockroaches are exposed to predators. Furthermore, antennae can become more important than other body parts such as vision are impacted.
Can cockroaches move antennae?
Cockroaches move antennae all the time. Most movements are vertical so that roaches only move these antennas up and down. An individual moving antenna is preparing for one of the following actions.
To determine moving direction
Cockroaches move all the time, especially at night. Since they don’t have a very good vision they need to rely on antennae to find a direction. Their movements are typically objective-based and entail one of the following moving reasons.
- A mate
Cockroaches move for food. They use odor-sensing abilities to find sources of food both indoors and outdoors.
Picking up pheromones is also important for mating. Cockroaches can move their antennae up and down when trying to pick up the pheromones released by female cockroaches which entail the willingness to mate.
To sense the proximity of predators
Cockroaches can’t fight off predators. The first defensive technique is to run. This is why cockroaches constantly move their antennae up and down to sense the proximity of potential predators in a given perimeter.
To map out objects lying ahead
One of the most important reasons why cockroaches move their antennae up and down is to establish the type of terrain and potential obstacles lying ahead.
Antennae can even hit some types of objects. The way these antennae hit these objects determines the following movement of the cockroach.
It’s unclear if cockroaches can sense vibrations while moving antennae or by holding antennae still.
How reliable are cockroach antennae?
There’s considerable research on cockroach antennae. Most studies conclude these antennas are very accurate and reliable for cockroaches.
For example, a cockroach trying to pick up food odors from the air can tell whenever these odors aren’t present in the air anymore. Antennae also help perceive the rate at which odors change.
This means cockroaches understand the rate at which perceived odors change and this means they can adjust movements better to find the food source in the shortest amount of time.
Cockroaches use antennae as a backup for their poor vision for getting around. Antennae also have a primary role in picking up odors and weather changes. Long antennae are used in mating habits, especially for picking up female pheromones.
Cockroaches can also sense humidity levels in the air using receptors in the antennae.
Most cockroaches defend themselves by running. They also rely on antennae signals to sense vibrations that can be dangerous as well as the presence of potential predators in their immediate surroundings.
Antennae are regularly cleaned by cockroaches to maintain acuity levels for the sensors inside.
Why do cockroaches have long antennae?
Long antennae (up to 150 segments in the flagellum) in cockroaches serve as a means to pick up food odors, mate odors, and navigate around by sensing terrains at night. Cockroaches also rely on antennae to establish humidity levels as well as potential weather changes as a means of defense.
How long are cockroach antennae?
Cockroaches have different antennae lengths depending on their species. One of the most common roaches, the American Cockroach, is known for having 1.5in antennae.
These long antennae can be partially injured with the cockroach still being able to use them almost at full capacity.
When one antenna is damaged cockroaches continue to rely on the other healthy antennae with a reduced negative impact on its capacity to pick up odors or to detect objects.
Do all cockroaches have antennae?
All cockroaches have antennae they rely on for daily activities such as finding food and potential mates. Antennae of cockroaches are regularly groomed to improve sensory acuity.
Why do cockroaches rub their antennae?
Cockroaches regularly clean antennae using their front legs and mouths. It’s believed this grooming ritual helps the antennae sense immediate surroundings more precisely. Cockroaches can also regrow antennae when injured.