The Mantis
“The voice of the infinite in the small...”
Life Cycle of the Mantis
The Egg Case "Ootheca"
Like most insects, the mantis starts out life as an egg. In most Northern U.S. states; the mantis is in this stage for the majority of its short life. These eggs are protected in egg cases called an "ootheca." These cases were laid anywhere from mid-September through early November and don't hatch until the following spring in mid-May through early June. Thus this leaves the mantis with only a few months to grow, mate, and reproduce before either cold weather and/or starvation ends their short existence.
Eggs of the Chinese Mantis are maroon in color and resemble grains of rice. They are neatly positioned side by side in "U" shaped rows that are then stacked on top of one another inside their egg case. The number of stacked eggs decreases the higher they are located in the casing which conforms to the shape of the outer nest surface.
The egg case is usually about the size of a golf ball and is tan in color. Some can be a little larger while others can be very small. Egg cases are normally found on a sturdy support that will survive the harsh winter. These supports usually are stems of weeds, small bushes or trees, vines, or even fences. The thickness of the support is about the width of a thin drinking straw. These egg cases can be found in abandoned fields, along roadsides, gardens, and bushes located right outside your front door. They can be deposited near the ground but are mostly located 2 to 3 feet high. I've located a few instances where some were laid on tree branches 15 to 20 feet off of the ground. Many can also be found along the edges of their habitats too.
Each egg case contains as little as 25 to as many as 400 eggs, sometimes more. The larger the egg case, the more eggs it contains
The egg case itself is a unique design. They look and feel like a hard rounded sponge but are light weight and can withstand a good impact. I've seen objects such as large limbs dropped on them and others that have been run over by farm equipment while sustaining little to no damage. The egg case itself is full of air pockets the size of tiny seeds that help insulate the eggs from the cold winter temperatures. These air pockets can prevent the eggs from freezing even when temperatures dip into negative numbers (Fahrenheit) weeks at a time.
The front of the egg case has a single row of small plates, all positioned on top of another that go all the way from the bottom and ends near the top. Under each of these plates is where the newly hatched mantis nymphs will exit the egg sack the following spring. When these egg cases are initially laid, these plates are covered with a papery material that is eventually weathered away, thus revealing these exits. The bottom the egg case is flattened and is smoother at the one end where it is attached to its overwintering host. The back of the egg case almost always wraps completely around the support structure.
Despite being well made, the egg cases are not always impenetrable. They often receive damage throughout the winter by hungry birds, such as woodpeckers, that use their sharp beaks to puncture holes in its surface. Some eggs are destroyed where the bird was able to leave a gaping hole. Other eggs are destroyed by parasitic larvae from wasps or flies that are able to penetrate the outer walls of the nest. And lastly, some egg nests are completely destroyed and shredded by squirrels, raccoons, mice, opossums, or ground hogs seeking an easy meal.
In my observations, even if the egg cases survive all of these perils, approximately only 1/4 to 1/3 of them hatch the following spring. Keep in mind, some egg nests were laid the previous fall where the mother had never mated with a male mantis, making the eggs within infertile anyway.
The Hatch
The following spring when the temperatures begin to consistently climb and warm the morning air, the eggs inside the case begin to develop into larvae-like creatures. These young mantids are covered by protective embryonic skins that press their limbs and antennae firmly against their bodies. The reason for this is that the passageways where they had been stored are very narrow and will lead them toward the openings located at the front of the nest.
The nymphs almost always hatch in unison during the early morning hours and during favorable weather conditions. Hatching usually commences between the hours of 0800 to 1100 Eastern Standard Time but can be as late as almost noon.
The nymphs emerge from the nest head first where their dark eye spots are visible immediately. Their heads are pressed down with their chins against their thorax. The nymph wiggles about like a maggot until it squeezes its body out from under the exit plates. It then dangles freely by a single embryonic cord that resembles a strand of spider webbing. This cord allows the nymph to emerge safely without falling to the ground since a drop like that could be fatal for their frail bodies. The nymphs are a pale cream color and have a soft exoskeleton that will take several hours to darken and harden.
After the first few nymphs appear, they are soon followed by many others behind them. They emerge several at a time. All of them cluster together by their life supporting strands as they struggle to free themselves from their birthday coverings. They dangle in a mass just directly under the egg case where they will sway in the breeze. Within minutes, the embryonic skins split open and the young mantid nymphs squirm their heads free, followed eventually by the rest of their bodies. The nymphs that free themselves first will either climb away over their other siblings, or drop to the ground or brush below. Their bodies are light weight and can be easily dislodged from their perches by the wind. The cluster of nymphs dangling below the egg case appears nearly as large or larger than the egg case itself. Some nymphs will form a chain below the other hatchlings that will make their descent below a little easier.
The more the nymphs free themselves and expand their limbs, the more chaotic the view appears to be. However, the entire hatching process is done in complete silence and is often gone undetected. Most egg nests become covered by spring leaves that sprouted and conceal them from view.
After about an hour, majority of the nymphs will have freed themselves and slowly begin their descent into the neighboring foliage. Some hang around the egg nest temporarily to rest while others gather together on nearby twigs or leaves. There are sometimes a few stragglers left emerging after most of their siblings have already moved on. Once they too are finished, only the cast skins are left behind to dangle from the front of the egg case. These lifeless skins can hang from it for a few days.
Hatching can still commence from the same egg case several more days after the initial emergence. These second or sometimes third or fourth rounds are often smaller. There are also instances of early stragglers that hatch days before everyone else does too.
Not all hatches go as well as I described. Some nymphs fail to molt or "eclose" from their nymphal skins and become trapped within them and eventually die. Some mass hatching are interrupted by passing predators such as birds, which make a quick meal of the helpless emerging nymphs. If the weather suddenly changes, winds or heavy rain can also dislodge the nymphs that are still encased in their birth skins and throw them to the ground where they will drown. However, I seen a group of emerging nymphs break away and fall where their embryonic cords became entangled on a nearby blade of grass. Luckily, this group of nymphs was unharmed and they continued freeing themselves like nothing usual had ever occurred.
Another example of a bad hatch would be either hatching too early or hatching too late. Nymphs that hatch too early in the spring can either freeze from a late frost or starve to death due to the lack of available prey. Nymphs that hatch a week or two later can easily fall victim to cannibalization. Their older cousins or siblings are bigger and stronger and may view them as their next meal.
Once all of the young have hatched, only the empty egg cases are left behind as a reminder of them. These egg cases will remain on their supports for many months or sometimes years. Eventually, these empty husks will wither, darken, and erode away...
The Nymphs
Shortly after hatching, the newborn nymphs disperse into the nearby vegetation where they seemingly become invisible. Several hours will go by before their frail bodies become stronger and grey-tan color. They resemble adult mantids but with an enlarged head and eyes, and lacking wings. They actually look like something that came from outer space with their alien-like appearance.
These first "instar" nymphs are approximately 1/4 on an inch long. They are very vulnerable at this stage in their lives. The majority of them will starve to death since suitable prey is not sufficiently available yet. Most other insect's life cycles have not begun this early in the spring which causes a huge problem for hungry newborn nymphs. It is believed that approximately 90 percent of new hatchings will die within the first few weeks of life. Starvation, predation, and inclement weather are the prime causes for their high mortality.
Nymphs will often have to resort to cannibalizing their siblings for survival. Otherwise, nymphs feed upon smaller creatures such as gnats and aphids.
Due to their small size early on, nymphs can fall victim to spiders and other insects until they grow bigger and become too large for these other invertebrate predators to tackle.
When food does become available, the young nymphs will begin their growth. As they feed, their old exoskeleton "skins" become too tight and they will have to go through a molting process to remove it. Their first molts usually occur within the first couple of weeks of their life. When the time and weather conditions are right, they will locate a sturdy support and then suspend themselves upside down by clinging to it with only their hind legs. After some contraction-like movements, they will chew a small opening in their old outer skin. The nymph will then free its head and antennae first. The thorax and forelimbs come next, followed by their 4 hind legs, and lastly its abdomen. The nymph will remain suspended and facing the ground as this procedure is completed. This ordeal can take more than an hour before the nymph is completely free. The nymph is helpless and again very vulnerable during this stage. One mistake can lead to a nasty fall that can cause deformities or death. They are also easily susceptible to predation.
Once freed, the nymph will cling to a nearby limb to rest while its pale body hardens. Now a little bigger than before, the nymph will leave behind its old cast skin that is a mere transparent representation of its old shelf.
Each stage of a mantis's growth is called an "instar." The mantis nymph will go through about 7 instar stages before reaching maturity. They will have to molt each time to achieve their next stage. Each time they grow bigger and as they reach their later instars, wing pads are formed and are visible where their thorax and abdomen come together.
As they grow, they begin choosing larger prey for nourishment. Once they had to be weary of other predators such as spiders. The bigger they become, the more those old predators become the new prey. Areas where mantids are plentiful, spiders are scarcer since they are items on a mantis's menu. Besides spiders, I've also noticed the decline of grasshopper and katydid species too.
By the time mid-August arrives, the nymph will be nearly the size of an adult. They will have now morphed into either a final brown, green, or tan color. Their colorization is influenced by their environment which has evolved to help camouflage them from larger predators like mammals. All the while they grow, they live among the foliage waiting for their next victim to wander along too close.
The bigger they become with each passing instar, their chances for survival increases more and more.
Hunting & Weaponry
A mantid's appetite can be quite ferocious! Mantids are silent ambush predators and can't make any audible sounds. Only under extreme starvation conditions will a mantis actively pursue prey within close proximity to it. With their long thin bodies and colors that match their environment, a mantid will often choose a perch and remain completely motionless for hours at a time. Sometimes days if their space is a good one!
A proper location can be essential for a mantid's growth and well-being. Those that choose to stalk their prey on flowering plants are often healthier and grow faster due to the abundance of flying insects that gather to seek nectar. Butterflies, bees, wasps, and beetles become prime targets.
Mantids have very good eyesight and are one of the few insects that are able to turn their heads 180 degrees to look at you. They sit and wait for their prey until a target comes within range. A prey's movement draws the mantis's attention and they will track the prey's movement by turning their head. The 2 front raptorial legs are the mantid's primary weapons. Each are equipped with 2 rows of dagger-like spines designed for gripping and holding prey. When the time is right, the mantis will rear them up into a position that makes the insect appear like it is in prayer. This "praying" stance is how the term "praying mantis" has been assigned generally to all species. However, praying is incorrect while the term "preying" is much more accurate.
Once the prey nears striking distance, the mantis may make slight swaying movements or turn its upper body towards the target as if it is getting excited. When the prey wanders close enough, the two front legs lash outward so lightning fast that the human eye has difficulty following the motion. The trap has sprung and its not often the mantis will miss it's mark. The front legs seize its victim into a vice grip. I've seen this happen numerous times over my lifetime and each time I vividly remember hearing the "crunch" as the powerful weapons seal the fate of its victim.
The prey often struggles to no avail. Some creatures like a cicada will let off an audible distress call but the mantis pays no heed to it. Once firmly held, the mantis raises its victim up to its pincher-like mandibles to begin eating. These mandibles are like a can opener as they pierce and cut the outer armor or flesh of its prey. The mantis often starts by chewing into either the head or neck of its quarry. Eventually, the mantis will either sever the spinal column, nervous system, or brain of its victim and thus ending its struggles altogether. Not all will be that fortunate. Sometimes the mantis will begin to devour is prey by first chewing off all of its limbs before eating any main organs. The poor creature will remain alive during much of this ordeal! Mantids only eat live prey and have no interest in scavenging. The mantis will devour just about everything with the exception of an insect's wings. Those are often discarded (as are the legs occasionally).
A mantis usually isn't too choosey with its diet and is known to eat not only large insects, but mice, small snakes, moles, and hummingbirds as well!
After eating, mantids will groom themselves like a cat. Like having good hygiene, a mantis will clean its forelegs using their mandibles. They then use those front legs to pull their hind legs to their head so they can also clean their feet. Mantids will even bend and clean their antennae so as to keep them free of obstructions.
These same formidable front legs can are also used in self-defense. If one is not careful while handling a mantis, the insect will use their raptorial legs to pinch a person's fingers. The grip is very powerful and is instantly painful. Some mantids are so powerful that they were able to puncture my skin! (Yes, I wasn't careful...) Just imagine what they could do to an unsuspecting bird that plucked one up the wrong way! Ouch! It is probably just enough for the bird to release its hold for the mantis to escape! The bird will probably think twice grappling with a mantis again!
The Adult
A mantis will often undergo its final molt in mid to late August. However, I've seen some adults as early as late July. The difference this time is that the mantis will now have wings and will be able to fly. After freeing itself from its final "skin," the mantis will position itself with its head facing the sky. Blood will then flow into the insect's wings as they fully extend themselves slightly beyond the length of its abdomen.
A mantis has 2 sets of wings. The inner set is more paper-like with a purple decorative pattern. They resemble a hand held Asian fan one would use to cool him/herself. The outer set is more hardened like a shield and fold roof-like over the insect's back. The outer wings also have a green lateral stripe down their outer edge that reminds me of pin-striping on a fancier automobile.
Adult mantids may come in a variety of colors. Most common are brown and green but also have been known to be teal green, tan, or even gray! Like the nymph, environment is very influential in determining the final pigmentation. Adults of the Chinese Mantis have a distinctive yellow spot located on their thorax between the raptorial legs above the coxa.
Male mantids are sleek thin creatures and decent flyers. They may travel between 1 and 2 miles from their ootheca during their life time. Their appetites are not as pronounced as their female counterparts.
The females on the other hand, have a ferocious appetite! They are larger and much more bulkier than the males. They can have a total length of up to 5 inches! They can fly as good as the males at first. But as the weeks go by, their abdomens become enlarged and plump full of eggs. As their abdomen's increase and weigh them down, their flights become less frequent and soon cease altogether. Thus they travel less distance during their life than that of a male.
Adult mantids can be found in fields, meadows, along roadsides and waterways, bushes, gardens, on the sides of buildings, and sometimes late at night where they are attracted to artificial lights. There are dangers to flying about at nighttime where they can fall victim to the attacks of bats or owls. Mantids have a single ear located on the underside of their thorax between their 2 sets of hind legs. This ear helps them to detect the high frequency sounds of an approaching bat. Once detected, the mantis may drop to the ground as an evasive maneuver. Their compound eyes have darkened similar to how a human's pupils dilate in order to increase their sensitivity to low lighting. This helps them to see better under those dark conditions.
Another defensive tactic an adult mantis may use to deter a predator is to make itself look larger. When danger approaches, most mantids mimic the plants they are stationed on often outstretching their front legs so they resemble twigs. However, if a mantis becomes cornered, they may rear up their front legs and lash out at an attacker. They will also open their wings and flutter them to make themselves more imposing. These tactics will sometimes work against more skitish predators like a cat or a squirrel.
Mating "Copulation"
Several weeks after reaching maturity, the female's abdomen is becoming engorged with eggs. Autumn moves in steadily as the daily temperatures begin to fall. Time is starting to run out and the female must sustain enough nourishment in order to produce the next generation for the following year. The life cycles of their prey are coming to an end which is making their desirable feeding habits difficult.
By this time, male mantids are aggressively on the move in search of a mate. They prefer to take flight at night to avoid the detection of birds. Respondent females emit a pheromone that can be detected a few hundred feet away. Males fly about until they catch this "scent" and are compelled towards it. Despite the potential for danger, the males do not resist.
Once a male locates a female, he cautiously approaches her from behind. If the female is well fed, he is in less danger but still must not be hasty. If the female remains unaware of his presence, he gets within range and suddenly leaps upon her back. If he succeeds, he will grip her around her waist with his forelimbs and anchor his body on top of her abdomen using his hind legs. Once firmly set, he will be out of reach of her grasps. He then contorts his abdomen until he's able to insert his sperm storage into her vaginal cavity located at the rear of her abdomen. They will remain conjoined for a few hours. During this, the male pays no attention to his surroundings and is determined to finish the task he has started.
Once completed, the male may remain resting on the female's back a while longer before seizing the right moment to quickly leap away and flee. If he is careless, he could easily become her next meal. A female does not view the male as a suitor and if she is hungry due to a lacking food supply, the necessity to eat him for her egg production becomes very high.
The female's pheromones will attract others who will also make the same leap of faith. Both males and females can mate more than once. The pheromone scent is so powerful that sometimes she can summon 2 or 3 males at once where they all compete and cling to her body. The weight of the combined insects will weigh down the limbs they are occupying. Once I observed 2 males positioned on a female's back with a third clinging to her underside. Luckily, she had a good grip on a branch but was apparently immobile on the account of it.
Cannibalism among wild mantids is rare. Males are most often very careful when locating and approaching their mates. The likelihood for cannibalism increases further into autumn. Food sources are gradually diminishing as a pregnant female's hunger escalates who is in dire need of sustenance for her offspring.
Careless males sometimes fall victim to the pheromone "trap" where she will seize him like any other prey and begin eating him by decapitating his head. There is often very little struggling as his body is still programmed to finish his mating urge. Even with his head and upper torso removed, his abdominal area may still commence with copulation and eventually drops off her back once completed. Some males don't even get this far and she will devour him almost completely, only leaving a couple of his legs and wings behind.
The need for feeding becomes so great that larger females may also feed upon smaller ones. Attacks against other females are not as common but I have observed it on rare occasions in late October.
These mating rituals begin in mid-September and persist into late October. As the season progresses, the number of available males decline either due to increasing cannibalism or by succumbing to inevitable starvation. Luckily, males don't require the sustenance females do and can persist much longer between meals.
A few days after mating, a female will be ready to complete the final phase on her life.
Ovipositing
After having mated with her abdomen swollen with eggs, the female is ready to make her first and sometimes only egg case. Egg laying or "ovipositing" start commencing in mid-September. This will persist into late October or early November or to whenever a killing frost or starvation ends their existence.
A female locates a suitable perch, usually a sturdy branch, bush, or weed (goldenrod is a common favorite), where she anchors herself facing the ground. A white frothy substance emits from the base of her abdomen as she adheres it to the structure she has selected. By using her pair of appendages called "cerci" located on either side of her ovipositor, she begins to "whip" the foam as her abdomen makes both circular and forward and back swaying motions.
Eggs will be deposited inside this foam as her abdomen moves steadily. The frothy substance, which will later harden into the protective egg enclosure, resembles a glob of cottage cheese.
I always found it interesting watching a mantis lay her egg sack. Despite my presence, she remains unalarmed and ignores my bewilderment. She is only interested in finishing her nest which often takes a few hours to build. Once completed, the female will wander away from her nest seemingly uncaring and apparently having already forgotten about it.
Hours after being made, the white egg sack will harden and darken into its standard tan color.
A female can make 2 or 3 egg cases in her lifetime, with time permitting. With the warm season drawing to a close, she may have enough time to produce one more. In Northern Ohio and other northern-most areas of their range, a mantis usually only has enough opportunity to make one and perhaps a second smaller one. The time between egg cases varies with both the availability of food and the amount of warmer weather. In cooler weather, insects become lethargic and their activity decreases as the temperatures drop. If winter comes early, there will be no time to make anymore.
When an egg case is laid, it isn't uncommon to find several more nearby. The female's pheromone release not only stimulates males, but also appears to motivate other females into depositing their nests as well. In some instances, I have been able to locate between 30 to 40 egg cases within 50 feet of one another and up to a dozen or more on a single bush. I've also located egg cases deposited side by side on the same twig within inches of each other too.
Female mantids will lay egg sacks containing infertile eggs if they have not mated. Only extremely isolated females have trouble summoning mates. Areas where mantids are abundant, the release of pheromones is high and attracting receptive males is much easier, thus making the likelihood of having fertilized egg nests greatly increases.
In some "old field communities," provided these areas remain undisturbed by human development, it's possible to find hundreds of egg nests within just a couple acres of land.
Death
In northern temperate regions, death to a mantis can come in mid-October or as late as mid-November. A hard frost will usually end their short lives as well as the lives of many other insects.
Starvation is a huge factor late in the season and cannibalism with individuals in close proximity is very relevant.
By the first week of November, after the leaves have already turned color and began falling, very few mantids are left alive. By the second week of November, I'd be lucky to find a single pair or an isolated individual.
A mantid's life span is generally not more than 5 or 6 months. If starvation or cold temperatures were not a factor, the mantis will die within another month or so regardless.
Once a mantis dies, their eyes turn grey or black and their antennae wither. Their bodies will become rigorous and will remain clinging to their final perch until either some scavenger or gust of wind dislodges them and blows them away.
However, long after their husks are gone and all of the foliage has faded and dropped away, we are left with the numerous egg cases, now visible, as a reminder of yet another life cycle completed and another waiting to start anew....