There once was a Lady beetle named Sasajiscymnus who favored a meal of hemlock woolly adelgids. So voracious was this beetle that she left her native homeland of Japan and flew to the lab of McClure to taste the American version of adelgid delectables.
With many a year of traveling between the labs of Dr. Sasagi and Dr. McClure the multiple generations of our Sasajiscymnus Lady Beetle demonstrated consistent contributions to both Japan and America. Thus, she received dual citizenship. The lovely Ms. Sasajiscymnus received her first federal permit to dine uninhibited in 1995 (this was only in Connecticut). Next she was allowed to visit New Jersey where her work continued to be remarkable. Unlike other visitors who've claimed to have extraordinary precision in terms of their dining preferences, this little beetle has repeatedly demonstrated a precise focus on Adelges tsugae in all its many life stages. She has been released to dine freely in the southern Appalachians.
What makes this biological control/eradication possible is the unique life cycle of the Sasajiscymnus tsugae beetle. It is highly synchronized with its prey. Unlike other predators of the adelgid, it doesn't take a season off. Since adelgids are parthenogenic (able to reproduce without sex), a single female can produce 300 per cycle and doesn't need to wait around for a male. This beetle is unique in that it is able to feed on every life stage of the hemlock adelgid. Did I mention she's voracious? A single beetle larvae can consume up to 500 adelgid eggs or 50 -100 of the nymph stage.
HOWEVER - Sasjiscymnus is picky about temperature and research shows that release times need to be made during warmer days. Dr. Hakeem et al. published a paper in 2013 in Environmental Entomology supporting temps between
10 and 25C (50 - 77F) as the most important factor contributing to the Lady beetles ability to hang out year after year finding and consuming the adelgids.
We can all purchase this hunter of hemlock-adeglids through treesavers.com.
The beetles are not inexpensive - but for those who can afford it - let's do it! We can increase their population densities at the expense of the hemlock woolly adelgid's offspring.
You may wonder why we see so many hemlock trees still infected while out hiking? These beetles are a challenge to rear in labs and thus it costs more than the USFS can afford to use as a generalist treatment of so many trees. Perhaps for your next birthday, anniversary, or other celebration you can request the company of on Sasjiscymnus beetle and release her into the wilds of your favorite mountains! Not into that - feel free to send Better Nature some beetles and we will photograph our release and send you this and the coordinates.
For clients whose trees I have not treated with systemic insecticides, I am going to encourage use of this beetle predator. I can't use them on the trees I've treated because 1. the adelgids have been killed by the systemic insecticide and
2. even if a few survived eating their insecticide-filled bodies, would kill our beneficial beetle.
Carole Cheah - adlegid life cycle (from ResearchGate)