Humans have co-existed with leeches for so long, according to Siddall, that just about every language has a word for leech. 3. theyâve made a comeback in medicine.
The lettuce aphid is a problem worldwide and has recently become problematic in the western United States and Canada (Liu and McCreight 2006; McCreight 2008). However, the first three species of aphids listed above are most economically damaging in Florida (Nuessly and Webb 2010). Although heavy aphid pressure can stunt plants, the major problem aphids cause is head contamination, which makes lettuce unmarketable.
That`s because the tree secretes a substance called juglone from its leaves and root system, and it can retard growth or even kill some plants. One final word about controlllng aphids on your flowers: If garlic or onions aren`t among our favorite thing to grow, try using pieces of yellow paper coated with a sticky substance like Vaseline. When inserted in the canopy of a plant, the paper attracts aphids and they become stuck to the material.