Dragonflies and damselflies are fascinating insects and Dave Halstead an instructor of Natural Resource Technology with SIAST was eager to tell their story at the Yellowhead Flyway Birding Trail Association Conference Saturday in Saltcoats.
鈥淭hey鈥檙e extremely unique insects. There鈥檚 nothing like them in the world,鈥� he said.
Halstead told those attending the main focus of his presentation was to enhance the appreciation of dragonflies. He added if he can get people to take out a net and binoculars to study the insects 鈥淚鈥檝e accomplished something altogether more fantastic.鈥�
In 贬补濒蝉迟别补诲鈥檚 own case dragonflies have become a life-long curiosity. It began in his early years as an aquatic biologist.
鈥淏ugs tell us a story about the health of lakes and streams,鈥� he said.
Halstead explained the larva of many insects, dragonflies included, 鈥渓ive on the bottom of lakes and streams,鈥� and can be impacted by dirty water, low oxygen content and similar water issues.
In 1990 Halstead began studying adult dragonflies 鈥渁nd I鈥檝e been pursuing them ever since,鈥� he said.
In general dragonflies 鈥渁re very robust,鈥� he said, adding they are large among insects and have four wings, the front pair differing in size from the back.
In the case of dragonflies the 鈥渨ings are stretched out to the side (when perched). They can鈥檛 fold them. It鈥檚 a very primitive characteristic,鈥� said Halstead.
Dragonflies and damselflies have actually changed little since arriving on the scene some 300 million years ago 鈥渁bout 100 million years before even the dinosaurs showed up,鈥� said Halstead.
鈥淎nd they haven鈥檛 changed very much from that original protocol.鈥�
There are about 70 species of dragonflies and damselflies in Saskatchewan, 40 in the Saltcoats area, said Halstead.
A local example is the boreal white face.
鈥淩eally it鈥檚 a Western Canadian species,鈥� said Halstead. 鈥淚t鈥檚 common about this time of year. It starts coming out in May and June 鈥� You won鈥檛 see it after June.鈥�
Halstead said in general the two groups come out in the late spring/early summer season, or are not seen until late in the summer.
Within the group are very large dragonflies, and down to small damselflies such as the Sedge Sprite that 鈥渉ides in the grass and look likes little hairs flying around.鈥�
Halstead said dragonflies and damselflies have a number of unique characteristics, including that 鈥渢he larvae are much more long-lived than adults.鈥�
In some cases dragonfly larvae live up to three, or four years 鈥渂efore they emerge as an adult.鈥� The larvae manage the long periods by digging into the mud and slowing down their metabolisms in the winter months.
The larvae of dragonflies are also 鈥渧oracious predators,鈥� said Halstead. They have a hinged jaw that allows them to shoot the lower portion out to grab food and draw it in to be devoured. The food can include small fish, tadpoles, and other dragonfly larvae.
When the larvae is ready the dragonfly emerges, stretching out much like an accordion, a transformation taking only about 20 minutes.
鈥淪o it鈥檚 very quick,鈥� said Halstead.
The change for the insect is dramatic, emerging into a world with far less pressure than the water world the larvae inhabited, and an ability to fly in a world where there is a thousand of times more oxygen.
The adults are incredible creatures with many amazing attributes, said Halstead.
The eyes, as an example can see 360 degrees 鈥渆xcept for where the body is,鈥� said Halstead, adding they have 鈥�30,000 individual facets鈥� so they can detect almost anything that moves. They can also see into the infrared and ultraviolet ranges, 鈥渟o they see a much broader range of colours than we do.鈥�
And, like humans dragonflies are able to focus on only one thing at a time among many, a trait long thought to be unique to humans, said Halstead.
鈥淭hey have very selective attention,鈥� he said, adding that makes them deadly hunters. 鈥淭hey鈥檙e 97 per cent effective. When they go hunting they almost never miss.鈥�
It鈥檚 a situation where there excellent eyesight effectively slows down what they see, almost like the scene in the Matrix, offered Halstead.
鈥淭hey see things at a much faster rate than we do,鈥� he said.
As hunters it helps that dragonflies can fly at speeds of 50-to-50 miles per hour, with the ability to move up and down, do rolls and hover.
The legs form a basket when flying in a hunt collecting prey to be eaten, usually with the head consumed first.
It is estimated dragonflies 鈥渆at 70 per cent of their body weight a day,鈥� said Halstead, adding much of their prey are nuisance insects such as horse flies, deer flies, black flies and mosquitoes.
And, in some cases, when food is scarcer, they will eat each other, he added.
