Observations of this stink bug species continue to accumulate, raising questions about why this insect is in the SoCal region now, and what its impact might be. Last Fall, the CA Department of Food and Agriculture posted a draft pest rating for the species, applying criteria that (at least for now) classify this insect as Low Risk, and proposing an overall Pest Rating of C. Read the complete draft, with natural history notes, at: https://blogs.cdfa.ca.gov/Section3162/?p=9206

Finding other references on the life history of P stictica (at least for English language publications) can present a challenge, though a recent paper from Brazil suggests these insects may utilize plants in the genus Senna as habitat and food source. While only a few iNat observers happen to note plant species associated with the occurrences of P.stictica nymphs or adults, where plants are identified they often seem to involve species related to Senna (in the Subamily Caesalpinioideae, e.g. Parkinsonia and Cassia), plus some other pod-bearing plants (such as the orchid tree Bauhinia, also a legume). The first occurrence of P.stictica in the US (1984) was collected in Texas off citrus. Some iNat records seem to show the insects on Ligustrum (privet); the Brazilian authors made similar observations, but when they tried raising a test sample of the insects on privet berries they reported little success.

Generally speaking, all the above mentioned plant types are prevalent throughout Southern California, but so far this doesn’t seem to tell us much about why P.stictica came to - or how it might have been transported around - the region. Whether iNat observations give us an altogether accurate timeline for the appearance of P.stictica remains to be verified, but the vast majority of the observations would seem to be unique (non-recurring) records. The first in the posted sequence come from late 2019, with only occasional sightings until a rapid increase began in August 2021. Of the 846 iNat observations of P. stictica in the Americas since February 2012, as of this writing 112 have posted locations for Southern California.

Ref: Panizzi, Antônio Ricardo & Grazia, Jocélia, 2001, Stink Bugs (Heteroptera, Pentatomidae) And An Unique Host Plant In The Brazilian Subtropics. Iheringia, Sér. Zool. 90, pp. 21-35: 26-28 https://treatment.plazi.org/GgServer/html/03F3E608FF9CFD73FE45C2D0259B2A4F