Weed and Pest databases can answer some questions for you. What bug is that? Why are my vegetables not thriving? All these questions and more can often be answered by searching a reputable weed or pest database. We suggest you try one of these:
Bug Guide – Identification, Images, & Information for Insects, Spiders etc for the US & Canada
Ugly Leaves may mean Disease – great charts to help with problems of onions, cucumbers, melons and tomatoes.