Update, I'm finding some seemingly contradictory information, chamomile can be used as a companion plant to attract insects, but triple strength tea can be used as an insecticide spray. Some gardening sites say chamomile can be used as a substitute for pyrethrum when making insecticide or insect repellant, which is what I initially thought might be the case as they are both in Asteraceae, as are all daisies. One of my text books when I studied horticulture was titled "Daisies are dangerous", a book on toxic plants so as soon as you mentioned chamomile alarm bells rang. Daisies are responsible for lots of kids being poisoned, usually because they make "tea" from whatever takes their fancy in the yard. There is still the possibility that weak chamomile tea may be beneficial, but I'd be very careful with it.