Question
I live near Wash DC I just harvested the last of my lettuce planted in pots the other day our nights have been well below freezing but starting in September I planted several lettuce seeds for fall harvest and I noticed two types of insects appearing on them tiny red bugs that hide where the leaves meet the stem.I was told to dust with Sevin powder which I don't like to do ,it got rid of them but in October there were small green colored bugs the size of a pinhead which camafloged themselves pretty well but did no damage except for a few sunken spots in the leaves,I am conscientous about observing my plants and I just flushed a steady stream of water to knock them off,but they still would reapear after a few days,my questions.What types of insects commonly attack leaf lettuce?,What organic method can I use to control or prevent them from  attacking again? Do some insects survive in the winter would I be better off getting rid of the old soil in the pots and buy sterelized gardening or potting mix and add all new soil in the spring?

Answer
Peter, I always recommend changing the soil in pots every season.  Potted soil is quicky depleted of nutrients, and therefore needs to be supplemented with organic matter or replaced.

In regard to the insects, it is difficult to speculate which exact insect in infesting your plants.  Aphids are one of the primary insects that attack lettuce, but without a picture I wouldn't want to say that's what they are with any certainty.

Regardless, there are several organic controls that are very effective against these types of insects.  They include insecticidal soap, pyrethrum, and rotenone.  Insecticidal soap is the least expensive and is very effective.  The other two are more lethal, but still not toxic to humans or the environment.  All of these products can be purchased either at your local nursery or through one of the following two web-based companies.

http://www.planetnatural.com
http://www.gardensalive.com

They both offer free catalogs which include hundreds of pages of organic products for gardening.

I hope this information helps.  Have a good holiday season.

Regards,

Mike