Bird populations in the agricultural regions of France are collapsing. Excessive pesticide use which is killing the insects that are the birds source of food appears to be the most likely suspect although the situation is exacerbated by increasingly large areas of monoculture crops (typically corn and wheat). Despite a government plan to reduce pesticide use by half by 2020, pesticide use continues to grow.
If the insects disappear, we disappear for the simple reason that many many insect species are critical parts of the food chain or play critical roles within the food chain (e.g. consuming decaying plants and animals). While insects as a whole are unlikely to be in any real danger of disappearing, many insect species which play important roles in our biosystem are increasing stressed by our way of life.