What are the effects of too much insecticide??

[gssgarden]

If any. Plants are about 2 feet, small fruit, but Aphids are here to stay and they're getting on my nerves!

It seems like I can spray every night! Using Sevin and have given them a full spray twice, top to bottom, stems, but every night I still see leaves covered in them so I hit the masses to keep them in check...so I think.

Can spraying too often harm the plant? Production? Cause an illness?

Thanks in advance,

Greg