E. Cornell, of Waikanae, asks :-
As a regular observer of spiders, I have noticed that the number of spider webs near my home in Waikanae has decreased dramatically. Many possible reasons come to mind but is there a known reason for this?
Phil Sirvid, an arachnologist at the Museum of New Zealand Te Papa Tongarewa, responded.
I don't have an explanation for the lack of spiders in Waikanae, but as far as I can tell, it's not a general and widespread issue elsewhere, or even in Waikanae for that matter. Indeed, a colleague of mine who weekends in Waikanae reports plenty of spiders where he resides. You expressed concern about a seeming absence of species such as Araneus (now Eriophora) pustulosa, Cyclosa trilobata and Arachnura feredayi, but I still continue to see them around. The latter two species do tend to be rather patchily distributed and can appear in large numbers some summers, only to seemingly vanish for years at a time.
If an absence of spiders is localised, there are several possible explanations although I have no evidence for any of them. First, pesticides may kill non-target species such as spiders, so you may want to enquire if there is regular spraying going on that may affect your property. Second, predators may be at work. Birds, wasps and even other spiders may be affecting populations of web-building spiders in your area. Lastly, it may be that for whatever reason, conditions are no longer to the liking of certain kinds of spiders. Absence of a suitable areas for web construction, lack of food and frequent disturbance are all factors that might influence a spider in deciding to try its luck elsewhere.
However, you may find that you have more spiders than you think. Now we are heading into the warmer months, I suggest one calm evening you look for spiders after dark with a torch. You may be surprised by what you see, as spiders that are exceedingly well hidden by day can be quite active at night.