The trap attracts or catches insects. The trap can be purchased from mail order seed sources. The insect trap is stapled to a dowel and placed in the garden. While not particularly attractive, they assist a gardener's identification of insects and the number of them. With close observation, a problem can be identified.
Some problems are obvious, such as a seedling stem cut off and the leafy portion missing.
Other problems can be more subtle, such as gradual leaf yellowing. Using I.P.M., a pest problem should be identified early. Look under leaves for insects, but once found, do not automatically assume they are pests. Gardeners need to be aware of beneficial insects and the true pests. Look at plant roots for signs of root rot.