1. Set up ~6 plates with 5 L4 hermaphordites each.
2. Heat shock 4-6 hours at 30°. 8-9 hours works but gives few progeny.
3. Return to 20°. Should get a few males per plate in the F1.
4. When you only have a few males , it is best to set them up with an excess of L4 hermaphrodites to ensure recovering more males in the next generation. Subsequently, male stocks should be maintained by selecting out an excess of males, along with a few L4 hermaphrodites, each generation.
7/31/94: Tried heat shocking n990 animals at 31-32°. I used nice fat late L4's with big white vulval crescents. Got much better results than previously; averaged >4 males per plate over 6 plates set up. Previously I'd tried this temp. with young L4's with only average results. So, maybe late L4's and 1-2 degrees higher temp. is the secret to fabulous results.