Get the real stuff from China!
https://world.tmall.com/item/5373981654.htm?spm=a312a.7700714.0.0.8NfpYl
It even works with roaches!
Selling for 1.40 RMB which is 0.21 in US dollars. 
I think you found it!!!
But DON’T hold it like that crazy person in the picture who is poisoning themselves through skin contact!
Bio-Hazard? 
From the comments on that Tmall page:
很好用哦，晚上畫的，第二天早上看到地上死了大概有二十來只小小強
Translation: Very good! I used at night, the next morning there are 20 small roaches on the floor.
Strong stuff!
Ok, if anyone has an ant problem and could use some of this ancient Chinese secret sheeet, there is a store in the Sunset that is selling this stuff (along with firecrackers, nunchuks, fully automatic weapons, brass knuckles and real switchblade knives). Just kidding, but true about the chalk. It is about a buck and a half for two small sticks. I went ahead and bought an entire box of it (about 40-50 bucks with a slight discount). My Fremont tenants were complaining about ants coming in recently and so I spent a good morning lining the entire exterior of the house with the stuff. I think I used about 6-8 boxes or so. Haven’t heard a peep from them yet… PM me if you want the Sunset store source. And please keep the information close to the vest shall we say???