When I grew up in Lake Tahoe in the 80s - near my elementary school, Monarchs would cover the near by trees in the THOUSANDS. HUGE populations. Apparently thei

When I grew up in Lake Tahoe in the 80s - near my elementary school, Monarchs would cover the near by trees in the THOUSANDS. HUGE populations. Apparently their primary food source is milkweed - which has been decimated due to pesticides. Monarchs take generations to migrate from mexico to america to eat, mate and rebuild their population, but humans have killed off their food source, milkweed, thinking of it as just a weed...