Last August, while removing some caterpillars from a basswood branch for transfer onto a fresh one, I came across an adult walkingstick. Being one that works with caterpillars for a good part of the year, I often happen across these well-camouflaged insects. Almost always they are males, around 3 inches in length with brown bodies and green legs. They are slim and have a set of tiny claspers at the tip of their abdomen. But this particular one was different. It was over an inch longer with a much thicker body and an even brown color. I noticed right away it was a female. Bingo!
Mating habits
Everything stopped as I carefully captured her and settled her into a cage on my front porch with a fresh bouquet of basswood branches. I have fond childhood memories of rearing baby walkingsticks with a good friend, and I was anxious to try my hand at it again, if possible.
I thought that by keeping this female in a cage for a few days, she might drop some eggs for me. Yet, all day, nothing. The following morning, I was stunned to find a male walkingstick clinging to the outside of her cage. The female must have summoned this mate through the use of pheromones, as he had made his way through the woods and up onto our porch. I opened the door and in he went. Within an hour, his claspers had latched onto her and fertilization was in progress. How fortuitous was that?
On and off, all day, the two joined up. And the next day and the next day and the next. After doing some reading, I found out that males will lay claim to a female, remaining nearby or joined with her to keep other males from adding their own genetics. On the fourth day, I noticed them taking a break and reached in to help the male to freedom. It really wasn’t something he wanted, but I didn’t see the point of keeping him contained. Shortly after his departure, the eggs started to arrive.
Walkingsticks belong to the order Phasmida whose members are also called stick bugs. Also known as “phasmids,” these unique insects are found on every continent, except Antarctica, and number up to more than 3,000 species. They come in sizes up to a whopping 20 inches and some of them sport wings.
Unique characteristics
The common or northern walkingstick (Diapheromera femorata) is native to North America. As their name suggests, they resemble sticks or twigs and are highly camouflaged when in their habitat. A fascinating behavior of slowly swaying back and forth augments this disguise by mimicking a branch gently moving in the breeze. Often, they rest with their front two legs stretched forward on either side of their antenna in an effort to form an extension of their twig-like appearance. So effective are these disguises, that most of us walk right by the insects without even noticing them.
Phasmids are herbivorous, feeding on the leaves of trees and shrubs. Much like a caterpillar, they can be observed chomping away on vegetation with gusto. Walkingsticks feed on a variety of host plants but I have found that basswood, oak and locust trees seem to be the most agreeable with their palates here on our farm.
Perhaps one of the most interesting facts about the walkingstick is the female’s ability to produce fertile eggs without the need to mate with a male. This form of asexual reproduction is referred to as parthenogenic, in which the development and growth of an embryo occur directly from the egg itself. Offspring from this form of reproduction are always female, appearing as identical replicas of their mothers. Should a female phasmid encounter a male, the two of them mate, producing both male and female offspring.
Unlike butterflies and moths whose life cycle is referred to as complete metamorphosis (egg, larva, pupa, adult), the walkingstick has an incomplete metamorphosis with only three stages including egg, nymph and adult. As the tiny nymph emerges from the egg, looking like a mini-me, it molts its skin several times as it grows, finally reaching adult size after several months. It is at this time during late summer when walkingsticks become noticeable, as the males leave the safety of their arboreal abodes to find mates.
Eggs
It is also during this time that the females commence egg laying. This consists of simply dropping them from the tip of her abdomen, one egg at time, into the protection of the leaf litter below. By randomly releasing them singly here and there, they are dispersed over a larger area. Where they settle, they will remain throughout the winter until the following summer when they will emerge as tiny green replicas of the adults.
Walkingstick eggs are a work of art, and I was taken aback at their beautiful intricacies. (something, as a child, I failed to notice). Like tiny, shiny seeds, the eggs, around 2.5mm long, are a contrast of cream and brown with a gray zipper and a yellow cap called the operculum, which pops open when the tiny nymphs emerge.
After I released the male from my cage, the female began dropping eggs. Sometimes she shot them out with force, while other times they simply fell to the bottom. I collected about a dozen a day while the female happily munched on her basswood leaves. When I selfishly had about 100 eggs, I released her back into the tree where I had first discovered her to continue her deposition.
Baby walkingsticks
Faced with the dilemma of how to overwinter these little gems, I decided to treat them as I do my moth pupae and place them in the crisper drawer of my refrigerator for the cold months. I carefully controlled the humidity and temperature in their container each month and in April, I removed them and placed them outdoors in a cage on my porch. I waited and waited and waited, and just about the time when I had about given up and was only peeking in the cage once every couple of days (instead of 10 times a day) I noticed a tiny splash of green contrasting with the cage’s dark-colored floor. The babies were arriving!
To date, I have around 20 nymphs — one or two seem to emerge every night. They have taken to their basswood and white oak leaves and are happily munching away. Already, I can see that the first nymphs out have shed their exoskeletons and have achieved new growth. Of course, I won’t keep them all. I can’t possibly feed 100 baby walkingsticks. Soon I will take most of them back to the woods, where they can continue to flourish and, hopefully, the amazing camouflage that Mother Nature has provided, will keep them safe and hidden until another generation eventually takes their place.
