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.
There are many species of aphids, some named after the plants they attack, such as pea aphids and peach aphids. In general, all are small (1/16 to 1/4 inch long) and oval-shaped, and can be black, white, green or pink. Although most aren't very mobile, some forms have wings.