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 deplete the plantâs fluids and nutrients from all parts, including leaves, stems, new growth, and flowers, so plant growth may also be impacted. Aphids tend to colonize on new growth and flower buds, so, flowers, buds, or new growth may appear stunted, distorted, or otherwise unhealthy.