A Glimpse of Nature -- Mantids
September 24, 2021
Two observers have shared photos of mantises living in Queset Garden. One was taken in late July; the other in late August. The most striking aspect of both images is the animals’ highly-effective camouflage.
Courtesy: Brian Woodward
I cropped this photo to highlight the insect who, from a distance, blended in with its boxwood hunting grounds.
This next specimen is difficult to distinguish from the feather reed grass where it is perched. The insect’s color matches the inflorescences and so does its vertical alignment.
Courtesy: Ian Dunbar
These images also illustrate several aspects of anatomy and behavior. Meadows and gardens are typical habitats for mantids, that is, species in the Mantidae family. Here the insects perch on tall weeds, grasses, and shrubs where they remain motionless until some insect prey comes along. Notice that they are hunting in daylight, using their large compound eyes to detect the motion of prey (and mates).
Let’s zoom in closer to see the insect’s eyes and its triangular head. A flexible neck allows the mantis to scan for prey by swivelling its head rather than moving its entire body which, of course, aids in the ambush. This closeup, also shows the specialized forelegs which reach forward and are lined with spikes that keep a firm grip on dinner. Entomologists use the marvelous adjective “raptorial” to describe this style of hunting leg.
The two most common species of mantis in Massachusetts -- the Chinese mantis and the European mantis -- are not native. Apparently, the former was introduced by accident and the latter for pest control. Both are well established in the US, having arrived over 100 years ago (Chinese: 1896; European 1900). These introduced species are still marketed to gardeners as an ecological pest control though, in reality, their prey selection doesn’t align with human notions of “pest” or “beneficial.” They are as likely to chomp on a pretty, helpful, or rare native as not. An additional source of distribution has been the exotic pet trade.
At this point, it would be reasonable to ask: “Which species are depicted in these photos?” To the best of my knowledge, they are both Chinese mantises, but the images do not capture some of the helpful field marks, and color is not the best determinant. Knowing the proportion of the grasses, it is obvious that the brown specimen is large. This would point to the Chinese mantis which can reach over 4 inches. Its tan forewings with green margins are, according to The Audubon Society Field Guide to North American Insects and Spiders, diagnostic.
The green insect is smaller (and a month younger). European mantises are smaller, but this insect’s face seems to have the vertical stripes which distinguish Chinese mantises. A European mantis would also have prominent black spots or bullseyes on the underside of its forelegs. Unfortunately, we don’t have a photo from that angle.
Obviously, it would be helpful to have multiple views of the insects -- from the side and from the front -- and a ruler. This is how we learn: observe, question, research, observe more closely the next time. I try to model the process in this blog and encourage you, the reader, to push a little further on each outing.
The mantids of Massachusetts live for one year and overwinter as eggs. During late summer and early fall, adult females are laying eggs. Thus, there is still an opportunity to see them this year. Moreover, now’s a good time to familiarize yourself with their specialized egg cases called ootheca. When the female mantis deposits her eggs, they are surrounded by a frothy substance that offers protection from weather and predators as it dries. Oothecae are hard, filled with air bubbles, and very lightweight. The Missouri Department of Conservation compares them to styrofoam and to “tan toasted marshmallows.”
Each mantid species creates a distinctive ootheca. This short article by the Brandywine Conservancy offers a good comparison of our eastern species. Look for them on your walks in meadows and along forest edges, where they will be attached to tall herbaceous plants, shrubs, and small trees. Here’s a Chinese mantis’ egg case that I saw in Hanson during April, 2020.
Ootheca of a Chinese Mantis
A female mantis can deposit multiple oothecae, each containing many eggs. If you should decide to bring one home, realize that, with warm indoor temperatures, you may soon have hundreds of cannibalistic nymphs to adopt.
P.S. Your photo of nature at the Ames Free Library could be the subject of a future post! Send the image and a brief description to firstname.lastname@example.org.