Why are illegal immigrants taking Detasseling jobs from our youth?

Since I’ve never even heard of “detasseling,” I don’t think illegals are taking too many of these jobs. If it was such a big industry, I’d probably have heard of it. 

If this is your biggest worry these days you are a lucky man.

The likelihood is that young people within a HIC would not do a low income and low skilled job. However someone at the end of the day needs to do the job, therefore people from NICs and LICs can immigrate to HICs in order to gain a better quality of life, in which they're simply willing to put more effort in and do the job that young people within the HIC usually wouldn't as any job is a job to them. It's bold to assume they're illegal as your prejudices may be affecting your questioning.