Praying Mantises in Goldenrods: A 2019 Highlight

As the year ends, I am reviewing some of the highlights of 2019 nature walks in Eliza Howell Park in Detroit. Observing Praying Mantises in patches of Goldenrods for three whole weeks in September is definitely one.

Looking ahead to 2020: The plan is to get the word out as soon as the 2020 “Praying Mantis in Eliza Howell Goldenrods” season begins, inviting anyone interested to come to observe at one of several different identified times.

I spent many hours in 2019 observing the fascinating behavior of Praying Mantises.


I see Praying Mantises in Eliza Howell when the adults begin their end-of-the-year behavior – seeking mates and laying eggs – in September. This year I noted the first one on September 11, seen here in an upside-down position that they sometimes take as they wait for insects.


The Praying Mantises seemed more common this year, though perhaps the timing of my visits and/or my observation skills improved; I saw several on almost every visit until the end of the month.

On September 16, I saw the first of the many mating pairs. Though the color of the male and female are different here, that is not always the case. The male is smaller and has longer antennae. They mate in upside-down positions or in upright positions or in horizontal positions.


The female often multitasks while mating. Looking carefully at the above photo, one can see that she has caught and is eating an insect.

It is easy to get pictures of mating pairs because mating is not finished quickly. I have sometimes returned and found a pair still in the process 2 hours after I first noticed them.


Praying Mantises are attracted to goldenrods no doubt because so many insects are attracted to the blooms. A Mantis will wait patiently until an insect gets close and then strike with one or both of the powerful front feet. The next picture shows one starting to eat, head first, what might be a bald-faced hornet.


Last year I wrote more extensively about “Praying Mantis Egg Laying” (September 13, 2018) than I am here. While they sometimes attach their egg cases to goldenrod stems, they will often select a sturdier plant near the goldenrods. Here is a female making the egg case into which she then deposited eggs. The whole process took about 3 ½ hours. The position for egg laying is head down in every one that I have seen.


It has only been in 2018 and 2019 that I have focused my attention on the close relationship between Praying Mantises and blooming goldenrods. In 2018 the mantises were present a little earlier in the season than they were in 2019, and for a shorter period of time. So I hesitate to predict when they will show up on 2020, but, as noted above,

the plan is to get the word out as soon as the 2020 “Praying Mantis in Eliza Howell Goldenrods” season begins, inviting anyone interested to come to observe at one of several different identified times.



Surviving the Winter? The Praying Mantis

This is a follow-up to the posting on September 13 this year – “Praying Mantis Egg Laying.”

Adult Praying Mantises do not live beyond the fall; the next generation is in the egg cases and will emerge in the spring. They will emerge if all goes well. Since September, I have been checking on egg cases in Eliza Howell Park.

My observations began on September 5, when I watched two different females lay their eggs. This is what the fresh new egg cases looked like then.


That same day, I noticed a pair mating so was confident that those two egg cases would not be the only ones this year.


In the weeks that followed, I many times walked the narrow path through the field of wild flowers and small shrubs/trees. I gradually saw more and more egg cases, especially when they became easier to see after the leaves dropped. These five were found in early November.


As of now, I have located 11 different egg cases visible from that path. Almost all of them are on the small trees (buckthorn, for the most part) growing in the field. Since each egg case probably has dozens and dozens of eggs, 11 cases would suggest a large number of little mantises emerging in the spring. If all goes well.

Some of the birds that spend the winter in the park are insect eaters, birds that often seek insect eggs and larvae. Praying Mantis eggs, though protected in the oothecal, are vulnerable to birds with beaks that probe.

Recently, I have been seeing evidence of predation.


Of the 11 egg cases I am aware of, 6 have been opened like this. And it is only November. The number of Praying Mantises estimated to emerge in the spring in Eliza Howell is decreasing rapidly.

While I have not directly observed this, I suspect that Downy Woodpeckers are responsible for invading these egg cases. Insect eggs are a part of their diet and they frequently forage on small trees and on plant stalks.


Photo by Margaret Weber

Another threat to the survival through the winter is the weather. One of the eggs cases is on a goldenrod, a large perennial that typically does not stay standing all winter. Last week, during the first snowfall of the year, it was bent low by the heavy snow, but it came right back up when the snow melted. The first picture below is from November 9; the second from November 10.

The stem will get weaker as the season – and the snow — continues. I do not know how well developing Praying Mantises are likely to do when an egg case ends up on the ground, but there is a reason why they are placed off the ground when the eggs are laid.



We know that only a very tiny percentage of acorns sprout. In July, I reported that very few, if any, of the toad eggs laid in the breeding pond left the pond as toadlets this year. It should not be a surprise if only a small percentage of Praying Mantis eggs laid this fall will result in live mantises in the spring of 2019.


Praying Mantis Egg Laying

Since my previous post on Praying Mantises in the park (“Praying and Preying,” September 4, 2018), I have found several more mantises and have watched them in different activities. I have seen a pair mating and two different females laying eggs. Their egg laying is fascinating.

Praying Mantis females produce both the eggs and the egg case. The case, called ootheca, looks a little like styrofoam. It is securely attached to plant stems and is about an inch long. The female fills the case with, perhaps, 100 to 200 eggs. In both egg layings I observed, the female had assumed a head-down position and the case was attached to the plant about four feet from the ground.


When finished, she leaves the case in place, where, if all goes well, the eggs will survive the winter and the young will emerge in the warmth of spring. It will be more than 6 months before these young emerge. When they do, they will look like tiny versions of the adult. And they will have the same indiscriminate carnivorous habits – their first meal may be a sibling.

In the next picture, the female is just pulling away from the case, egg laying complete.


It was hot when I watched these two females, but Fall is coming and the first frost is not that far away. Females usually die around the first frost. They are completing the life cycle – and starting the life cycle.

The ootheca hardens and turns a little darker shade. The next picture was taken 4 days after egg laying.


Laying the eggs is lengthy process, which is not surprising when we realize that not only does the case have to be made for housing the eggs, but each egg is placed in a different chamber in the ootheca.

A few days after the observed egg laying, I spotted a third Praying Mantis egg case on a shrub. I do not know how old this one is, so do not know if the eggs had hatched, but the case had been broken into, perhaps by a bird.


Since it was no longer functioning as a protective environment for eggs, I cut the ootheca open to get a better sense of its structure. Though the details are hard to see in this picture, it might provide some sense of the way the case is structured.


Praying Mantis egg laying is not a simple process of laying eggs on a plant. As I observe what happens to the egg cases over the next months, I will likely learn more about the life cycle.

As I noted in my first post last December (“A Sense of Wonder”), Eliza Howell Park “provides an excellent opportunity for me to experience the natural world in its wonder and excitement and beauty, right in the heart of a major urban area. I continue to be excited by what nature presents in season after season.”

Recently, the Praying Mantis has been the latest “critter” to contribute to my sense of wonder and excitement.



Praying and Preying: Those Two Front Legs

I hadn’t seen a Praying Mantis all year in Eliza Howell Park until last week. Now I have found three. The species is Chinese Praying Mantis, the larger of the two species found in Michigan, about 3 and ½ inches long.

It often takes careful searching – or just happening to look in the right place at the right time – to find the camouflaged insect.


They are called “praying” because of their habit of holding their front legs together in front of them, similar to a praying position some humans assume. This posture can be seen in the next picture, taken from the front.


The Chinese Praying Mantis was introduced in this country in the late 1800s to help control unwanted insects, having long been recognized as very effective in catching and consuming many different insects.

The mantis is an ambush predator. Part of the feeding strategy is camouflage. The shape and color make them difficult to see when they climb small limbs. This one was positioned head down.


Its “praying” position is also part of its hunting strategy. It can remain motionless for hours, if necessary, until prey comes close. Then it strikes with great speed. The same front legs that remind people of praying are extremely effective in preying.

Note the differences between the front legs and the other four.


Mantises are carnivores. They eat insects (all kinds) and spiders, and sometimes small frogs and birds. They even eat other mantises. At times, the female eats the male that mates with her!

The front legs have spines (spikes) that assist in grasping prey, which they then eat alive.


Mantises usually mate in September or early October and the female lays eggs which, as an egg mass in a case, survive the winter and hatch in the spring (May or June). The adults I saw these last few days have probably only recently reached full maturity. That fact, and the need to find a mate, may account for them being more visible at this time of the year.

It is always exciting to find a Praying Mantis in a park or garden. It is attractive, a little exotic, and has a very interesting life history. They can even look somewhat harmless…


…but those front legs are deadly to other insects.