October 2016 -- First noted lep larvae dwelling in dead stems of jewelweed, Impatiens

but the larvae I collected and attempted to overwinter did not survive into the spring

26 May 2018 -- Dead stems of jewelweed, overwintered in situ from the 2017 growing season, are still easily identifiable in the duff layer, a bit banged up from the long winter but still present as the fresh green sprouts of this year's plants emerge around them.

From what I was able to observe during the spring of 2018, larvae of the stem borer overwinter inside these dead stems and pupate there in May and early June; adults emerge in June (apparently early in the month, as by the time I was able to start opening stems in late June, most of the pupae I found were already spent!).

28 June 2018 -- By late June, the adult moths have emerged from the dead stems and oviposited on or in the freshly growing jewelweed shoots. Their eggs have hatched and larvae have begun boring in the jewelweed stems, causing a discoloration visible from the exterior (since jewelweed stems at this point in the growing season are relatively thin and translucent).


05 August 2018 (current series) -- Maturing larva has worked its way down the older, thicker jewelweed stem, leaving the stem interior "speckled" with brownish frass deposits