Did you know that there are 180 species of odonates in Maryland? Odonates are an order of insects that include dragonflies and damselflies. You can spot the difference between the two by looking at their eyes. Dragonflies have big eyes with no discernible space between them, while damselflies always have a noticeable gap between each eye. Also, damselflies are typically smaller than dragonflies; however, the largest odonate in the world is the helicopter damselfly.
Years to Mature
Odonates are predators and are at the top of the insect food chain. Interestingly, these insects spend the majority of their life cycle in the larval stage. James McCann, zoologist at the Maryland Department of Natural Resources Wildlife & Heritage Service, explained that damselflies and dragonflies have three basic life stages: the egg stage; the larvae, or nymph, stage; and the adult stage. While the egg stage can last between five and seven days, or even up to a year, the larval stage is longer. According to McCann, this stage “is generally the longest, lasting a few months to one or two years for most Maryland species.” The larval stage, said McCann, “can last up to six or seven years for some arctic and subarctic species.” Within the larval stage are several stages, or instars, in which the larvae molt an existing exoskeleton to make way for a new one as it grows. Each molt is known as the beginning of a new instar and, as McCann explained, “the number of instars varies by species and environmental conditions, ranging from nine to 17.”
Odonate larvae are aquatic, so when ready to metamorphose into an adult, it must crawl out of the stream, river or pond that it inhabited. Once out of the water, it will emerge from “its exoskeleton as a soft bodied, somewhat translucent adult or teneral.” It takes just a few hours for the teneral adult’s body to harden, fill in with color, and take flight. Over days and weeks, the odonate will become sexually mature. In general, the adult stage of an odonate’s life cycle lasts from a few weeks to seven months. This depends on the species, location and the conditions of the habitat. In Maryland, the majority of our adult odonates live between one and four months.
Once an odonate reaches maturity, it’s time for it to mate. Odonate coupling is an aerial affair that requires highly coordinated maneuvering. After identifying a female of his species, the male boards the female’s back, and pinches onto the back of her neck with end of his body. Then, the female must wrap her body around the other side of her partner and attach the bottom part of her body, where her sex organ is located, just underneath his thorax, where his sex organ is located. The end result of the coupling is a heart-shaped formation, better known as the wheel formation.
Conservation for Odonates
Clubtail dragonflies, belonging the family Gomphidae, are a diverse group of odonates. There are 33 species of clubtails in Maryland. What makes this species so fascinating, according to McCann, is that they have very specific habitat requirements, which include clean flowing waters. Some, he explained, can only be found in “pristine, high-elevation, Appalachian headwater streams in the far western part of the state,” while others, in the central or eastern parts of Maryland, are found in, “high-quality large streams and small rivers” or “are confined to the cleaner sections of our biggest rivers like the upper Potomac.” Because these odonates require such a high-quality habitat, McCann said that they serve as canaries in the coal mine because they are “good indicators of the conditions of our streams and rivers, most of which are degraded,” due to development, farm runoff, industrial pollution and dams.
McCann said that “nearly 70 percent of Maryland’s clubtail species are rare or on the state’s endangered species list.” This includes “several species that have not been sighted in 30 or more years,” and, warned McCann, “may be gone from the state.” While clubtails are not the only species in need of protection, their dramatic decline places them among the most rare and endangered species in Maryland. Learn more about odonates at dnr.maryland.gov.
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