Spiders can hold their breaths to avoid inhaling pesticides.
Spiders nor insects actually breathe; therefore they cannot "hold their breaths." There is no active pumping of air into and out of those small bodies. Insect respiration takes place by passive diffusion into and out of a network of tracheal tubes. Most spiders also have tracheae, but their main respiratory organs are book lungs. Pesticides don't work well against spiders because they're formulated to kill insects, not arachnids.