Some very nasty weeds are coming into seed at this time of year. Swallowwort is a relative of milkweed and often confuses monarchs looking to lay their eggs. While milkweed both feeds and acts as nursery for monarch butterflies, swallowwort is a death trap. Eggs laid on that plant will die shortly after hatching when they feed on the toxic leaves. If you see the plants in bloom (photos of each) or with seed pods, cut down and bag it and send it to the trash. Mark the spot and next year start early mowing or cutting it down as it emerges. If you keep at it, it will eventually die.