Although spiders play a vital role in controlling pest populations in Ontario, coming face to face with the eight-legged critters can be frightening, and unfortunately, this is precisely the time of year when you're more likely to spot this type of spider in your home. 

The yellow sac spider (Cheiracanthium), which is fairly common in Ontario, is responsible for many of the reported spider bites throughout the province, and can deliver a painful bite if threatened. 

The small spiders are usually five to eight millimetres long, with yellow or beige colour, and a banana-yellow coloured abdomen. The bottom of their longs are usually brown, and they are often marked with a dark line on their backs. 

Instead of webs, yellow sac spiders build silken tubes or sacs that offer protection, and like to stay hidden during the day. 

In the early fall, the spiders usually venture indoors in search of small insects when their outdoor food sources start to dwindle, and are commonly found where walls and ceilings connect, and behind shelves.

Yellow sac spiders are known to be on the more aggressive end, and their painful bites can cause swelling, red patches, itching, and numbness.

If you encounter one of these spiders, your best bet is to leave it alone or to keep them out by sealing cracks around entry points with caulking.