Spiders entering Alberta

[Robin Leech]

Three species of introduced spiders were found, live and thriving
in Alberta this past week:

Theridiidae
Latrodectus mactans
(black widow)

Pholcidae
Pholcus phalangioides
(long-legged cellar spider)

Agelenidae
Tegenaria agrestis
(hobo spider).

The above-named black widow species in found widespread in the US and Ontario, but not in western Canada.  The cellar spider, originally from Europe, is widespread in the world, even in Tasmania, but has been found established only once previously in Alberta.  This is the second, confirmed hobo spider found in Alberta.  Both are females.

The only reason these were brought to me is that the finders were curious about them.  Just how many more are brought in that we do not know about?

We do not have a clue about how these anthropochorous species will affect our precinctive groups.  If examples from other anthropochorous organisms (sparrows, starlings, purple loosestreif, oriental long-horned beetle, etc.) are valid indicators, we should start being worried - even with spiders.

Along with these spiders, I have been made aware that in the last week or so at least 3 bites by organisms unknown have occurred. These bites have an inflamed area about 60-75 mm across, and a large pustule, about 10-12 mm high that forms.  The pustule recedes in about 4 days, and a flat scab forms.  

Robin Leech
Edmonton

Robin Leech