noun
fishing fly
An artificial fly used in fly fishing, designed to imitate insects such as mosquitoes.
渓流で蚊針を使ってヤマメを釣った。
I caught a landlocked salmon using a fishing fly in the mountain stream.
毛針 is a more general term for a fishing fly, while 蚊針 specifically imitates a mosquito or small insect.
Compound of 蚊 (ka, 'mosquito') and 針 (hari, 'hook'), with rendaku voicing to ばり. The spelling 鉤 is a variant character for 'hook'.