Ryan –
We receive our praying mantis egg cases around the first of the year and can ship them to you anytime after that. In addition, praying mantis eggs can take 6-8 weeks of warm temperatures, 65-75 degrees daytime, no lower than 45 degrees at night, to hatch. Plan ahead and hatch them early so that they are around when caterpillars arrive.
To speed up the hatch, we recommend placing egg cases — still in the bag — on top of a refrigerator, or some place that is consistently warm, but not hot. Do not place them on a windowsill as temperatures fluctuate too much.
Once the tiny mantis hatch, you should put them outside immediately. Praying mantis nymphs are cannibalistic.