NEMATODES - Are they for real?

Can anyone recommend a reliable brand of nematodes?

About two months ago, our lawn having suffered an attack of chafer grubs, we applied (without too much conviction, as we tend to believe what we see) the recommended dose of the invisible creatures to the lawn.

Some brown characteristic patches appeared with grass which could be pulled out very easily and, digging them up earlier today, I found a number of grubs which suggest that, either those grubs are not chafer, or that nematodes don’t really do the job, or that we bought an ineffective brand.

Any advice on these mysterious creatures would be welcome.

 

With nematodes it's all down to timing. I've found the vine-weevil preparation to 100% effective if I follow the instructions - use on damp soil, in September and at temperatures above 10°C.
I've had a look and Nemasys specifically says the anti-chafer nematodes will be ineffective in spring once the grubs have pupated (the photo looks like chafer pupae to me), as they can only penetrate soft-bodied larvae. I'd definitely give the nematodes another go, but this time in the autumn.