Black & Yellow

Another quick week has gone by and we’re on the road again from Kejimkujik to Prince Edward Island. Famed for its mosquitos, clear night skies and Mi’kmaq origins, Kejimkujik National Park did not fail to impress. In an act of sublime timing and luck we were able to arrive in one of Canada’s most ideal spots for night sky viewing during the incredible Perseid meteor shower. For three days the sky was periodically streaked with ephemeral cosmic lights and we soaked up every bit of it we could. Our days were filled with frogs, deer, the occasional snake and of course many an arthropod.

Agriope aurantia female consuming her Orthopteran prey
Agriope aurantia female consuming her Orthopteran prey

One arthropod in particular caught my interest: an arachnid, the Black and Yellow Garden Spider, Argiope aurantia. We had just about completed one of our hand collection events at the Farmlands trail (hand collecting is when we travel down a path and manually collect arthropods along the way) and came into a clearing where a farm once stood. In a lone bush among the tall grass that now dominated the clearing was the strikingly large Argiope aurantia, where it carefully maintained and monitored its web. The web was also the final destination for a number of unfortunate grasshoppers and flies.

As is true with many spiders, there is a distinct sexual dimorphism observable in the relative size of the males and females. The A. aurantia I photographed was clearly a female with a body length well over an inch; their male counterparts are often three times smaller than the female. The distinct yellow markings against black background on the abdomen remain conserved between the sexes, making for a relatively easy identification.

Note the distinctive markings on the abdomen and the white, hairy cephalothorax.
Note the distinctive markings on the abdomen and the white, hairy cephalothorax.

A female Black and Yellow Garden Spider will spend the majority of her life within a small range, generally staying within her web for the entire summer where she will eat, mate and lay eggs. The smaller male will construct his web either within or adjacent to the female’s web. There is no ambiguity to the male’s purpose in this relationship, after he mates he will die and potentially be consumed by the female. The female will lay thousands of eggs within several sacs encased in layers of silk. She will spend the remainder of her summer and life protecting the eggs; eventually she will die come the frost. The eggs will overwinter and emerge the next year.

Despite the size and intimidating appearance, these spiders pose no threat to humans. They have a large range with populations in Canada, the United States, Mexico and Central America.

-Forest

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