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.
Aphids, also called plant lice, are small (up to Â¼ inch) soft - bodied insects that infest most garden plants. Some aphids spend their entire lives on one type of plant; others infest different varieties. Most gardeners can readily identify the green aphids, but black, brown, yellow and gray aphids are also common.