Abstract: The subject invention relates in part to a novel protein for binding Bacillus thuringiensis Cry toxins, and fragments of cadherins for enhancing Cry toxicity against dipterans. The subject invention also relates in part to the discovery that fragments of a midgut cadherin from a dipteran insect synergize Cry proteins that are active against dipterans. Thus, the subject invention includes the use of fragments of cadherin ectodomains for controlling dipterans. Such fragments (that bind Crys) can be administered to a dipteran insect for ingestion. In some preferred embodiments, the source cadherin is a dipteran cadherin. Also in some preferred embodiments, the fragment is administered with a Cry protein that is active against a dipteran. Variants of the fragments of naturally occurring cadherins are included within the scope of the subject invention.