Yah insect larva or ? It's something I have never seen . I use neem oil about 1 time lightly every week for preventative maint. So these bugs don't mind neem oil I guess . Well it's not to bad because it was only one leaf but I would like to know what they are still. Googling for a hour I found nothing The same. Ed rosenthalls book I have had nothing and nothing in the growers bible either ..c'mon somebody must have had this before and knows what it is.It looks like somekind of insect nest or larva, or whatever
Clean it off and spay her down with some neem oil.
Your right bayou I need to be very carefull doing indoor/outdoor . So far I have been able to finish a few grows with great success this way . I take the time to keep the rooms very clean . Its worth the extra work to save on electricity every day . I really never have any pests at all. I got spidermites from a clone once and won the fight . And a occasional worm in the bud .if I still had the leaf to look at I would use a loupe but I took a photo and flushed it down the toilet .I know a lot of people do it but just be very careful with indoor/outdoor plants. They invite outdoor pests inside to wreak havoc on your indoor facility/plants. During the indoor period in the room, there is not a strong symbiotic environment set up to keep any pests or keep any diseases in check.
Jewelers Loupe that and see if anything crawls around. Could it be some random OD pest that typically doesn't attack cannabis?