Poison bait is the best control, but not Onslaught
By Neal on 12/14/2014
I have had excellent success for 10 years with baited yellow jacket traps, which have reduced my backyard yellow jacket problem almost to nil here in the SF Bay Area. I switched from other microencapsulated insecticides to Onslaught when the latter became registered for the purpose. I had mixed results with Onslaught -- better than not baiting (or using traps), but yellow jackets were still an annoyance when we were eating outside. Then I read a UC Riverside study (http://www.pestboard.ca.gov/howdoi/research/2009_yellowjacket.pdf) that reported that "The only registered bait (Onslaught®, microencapsulated esfenvalerate) was not effective as a bait toxicant against the western yellowjacket, V. pensylvani". They found that fipronil was the most effective, at a dosage level of only 0.025% in bait such as chicken or fish. Note that fipronil products such as Taurus SC are not listed for this purpose (i.e. the label does not officially say that it is OK in a yellow jacket bait).
The bait stations are poor quality plastic. For the price, I would expect that they not crack down the side when removing the lid. I'll give 3 stars for the insecticide. Zero for the expensive bait stations. I will convert old pill bottles in the future.
I tried the fruit, jam, meat selection process with no insecticide and the YJ went straight for the tuna! I dosed in some onslaught and they ate it a bit but soon left it alone. Also there were some dying at the traps so I tried again exactly as recommended. 12oz tuna to 1/4tsp onslaught. Same result. I'll try again in the spring and hope for better results.
While the order and shipping was great, the product did not work as well on yellow jackets as I thought it would. We've been inundated by yellow jackets this year. After two weeks of treatment, they have slowed down to a lesser amount of presence, but still more than a typical year. I was expecting the Onslaught to eradicate them completely or nearly so. Maybe my expectations were too high.