Sentence:  Instruments called "hopperdozers" were invented, which had receptacles filled with hot tar, and were driven over the ground to catch them as flies are caught with <WSD>tanglefoot</WSD> paper, and many millions of them were destroyed in this way, but it was about as effectual as fighting a Northwestern blizzard with a lady's fan, and they were all abandoned as useless and powerless to cope with the scourge. 
Meaning of the word marked with <WSD> tags:  A sticky substance put at the base of trees or other plants to trap insects and prevent them from climbing up.