by Prof. Dan Johnson, University of Lethbridge@DanJohnsonAB
Natural enemies of insect pests perform a great ecosystem service and therefore deserve of efforts to conserve them, or at least not actively kill them. We often forget one of the most important groups of organisms that tirelessly battle insects that feed on our crops, on forests and even on ourselves.
Hundreds of species of spiders spread out in populations of
thousands to hunt and destroy insects, including those that increase in numbers
in response to the encouragement provided to them by crops and urban plantings.
Spiders present essentially no personal risk to us in Canada. Even nations like
Australia, where the dangers are legendary, go years and years with no
fatalities from spiders, although the same cannot be said about the risks from
bees, wasps, dogs, horses, wildlife, and even dust mites, all of which have
tallied more significant body counts worldwide.
Maybe the reason we ignore spiders, and sometimes fear them, is because we have not seen them up close enough to appreciate their various forms, interesting activities and contributions. The group called the jumping spiders, for example, have behaviour that is complex and seems intelligent, even curious. Orb weavers, which are often noticed sitting fat and patient in their webs, have been seen in increasing numbers in recent years.
They are famously good at capturing flying insects, while the funnel weavers use webs closer to the ground to do the same, sometimes covering grassland with shimmering webs that also catch the light. Crab spiders wait in the vegetation and grab unwary prey insects, while spiders in other taxonomic families, like running crab spiders and wolf spiders, chase down their small prey. Spiders have maintained their numbers and activities through thousands of generations since the ice ages ended, and will continue to keep up the work of turning over the food webs, running ecosystems, and greatly reducing our partially self-imposed pest problems. The good news is that they are adept at adapting to changing climate and opportunities. The poster below will give you a start on recognizing some of the different types, and names of typical taxonomic families.
Created March 27, 2019 | Category: Bug of the Month