Karen Strickler provides a list gleaned from the literature about mason bees (see below), unfortunately many plants have genus only listed and some probably won't do well in PA. J. Bosch & W. Kemp have a comprehensive list in their book: How to Manage the Blue Orchard Bee. I would look at spring-blooming plants that are good nectar/pollen sources generally, and especially those in the rose family (strawberry, apple, cultivated cherry, peach, plum, apricot, nectarine, quince, serviceberry, raspberry, cotoneaster) that will bloom in the late March to early June interval. I'm not too sure about whether pear or some wild cherries (e.g Prunus serotina) are attractive. Oregon grape (Mahonia aquifolium), eastern redbud (Cercis canadensis), willows (e.g. pussy willow, Salix discolor), spring-blooming viburnums (e.g. Viburnum carlesii, V. trilobum), currants/gooseberries (Ribes spp.), bush-type honeysuckles (Lonicera spp.), and buckthorns (Rhamnus spp.) should be good tree/shrub resources for these bees that will do well in PA. Caution: non-native honeysuckles and buckthorns can be highly invasive and detrimental to conservation areas. Ideally, you want a mixture of blooming plants that will span the activity period of the adult bees. There should also be moist soil available nearby the nest site. I would think that spring-blooming heaths (e.g. Erica darleyensis), bog rosemany (Pieris pallida), and blueberries (Vaccinium spp.)would be at least as attractive as Japanese andromeda, which Brian Griffin is so fond of. Herbaceous plants that I have observed mason bees foraging are meadow sage (Salvia pratensis), other early-blooming salvias (e.g. Salvia x superba 'May Night', Salvia officinalis), cultivated and wild early-blooming mustards, cresses, and radishes (e.g. arugala, Brassica spp., Sisymbrium spp.), dames rocket (Hesperis matronalis), and dandelion (Taraxacum officinale). Here is a link that might be useful: bee garden for mason bees

It's not for lack of flowers. I've been raising bee attractant plants, but not even my clover had many bees last year. My confederate jasmine had a fair number of bumblebees but the regular honeybee population was way down. I'm going to try a couple things this year. I'll put out some mason bee nesting sites and see if any are used. And promote the flowers again, of course.

I have had issues with GW lately failing to email me when subsequent posts to threads come up, so you're not the only one it doesn't like! The mason bees have one generation per year. It makes them so easy to have around. You certainly don't need to bring in the bee cells to your home if that's not your thing. If you don't, there could be several predators that will mine little holes into some of their tubes and attack the developing larvae. Some suggest waiting til fall to bring them in, but if I remember, I just grab the blocks that are filled up and store them in the basement once the adults are no longer visiting the blocks (usually around the beginning of June). Bringing them in greatly reduces the risk of predators. The adults are only out from late March to early June. Once you've got all your planting done for the season, but the end of May early June, then it's time to start to monitor the boxes for adult visitation drop off. Yep, we've certainly had a few bees in the house! If you forget them in the basement, they will emerge by about mid April no matter the temperatures, so you gotta get them outside by the end of March. If a couple do emerge earlier, I put the freshly emerged adults into the refrigerator with a cotton ball soaked in sugar water 2:1 water to sugar. The cold slows them down and the sugar water sustains them for a few days to a few weeks. I then put the entire little box in the fridge until it looks like Mother Nature is cooperating, and providing them with blossoms to visit. To avoid any issues, I try and put the boxes and bee cells out when the flower buds on the fruit trees start to look like they are about to open. I wish I had some pictures of the larval cells. They are like little bullets with mud on either side. As a note, the roofs on the boxes for mason bees are totally not needed, though I think the little workers appreciate a little rain cover. I've seen people stack 2x6 blocks in their yard without any rain cover or roof, and they still keep their bees happy. In the late fall, you can often find folks selling starter mason bee pupal cells on Craigslist and EBay for around 20 bucks. Of course you can purchase them from online sellers as well. I never have had that many blocks where I had a bunch of surplus bee cells, but maybe I'll build a few more boxes this fall to increase the reproduction opportunity next spring. I'm not in it to make money, but I would be willing to donate some starts to someone wanting to give them a try if they produce enough next spring. Zach, as much as you seem to like insects, this little cheap project should be on your to do list! Of course, I'm happy to answer any questions that may come up along the way. Dan

I ordered hornfaced mason bees this past Feb. Had 9 femals nesting in bee house for about a week. Then my lovely wife decides to put sevin dust on the front flower bed cause she THINKS there's bugs on her flowers. One by one I notice the bees are not returning to the nest. After a week all were gone with only half filled tubes. I told her what was happening and she calmly told me about her sevin dust on the front flower bed. I was beside my self, mason bees are not cheap! We had a good little understanding after that conversation. I was really proud of my self that I didn't blow up on her;) there's always next year. I haven't seen any in my back yard yet and have been growing a lot different blueberries for 3 years now. Plus peaches, blackberry, citrus and assortment of veggies. I'm Seabrook tx by redbluff and plenty of woods near by to support native bees. I have seen carpenter, bumble and honey bees but not one mason bee yet. Only time will tell.