Invasive plants supporting invasive bees

Male Bee feeding on Spotted Knapweed
A male Bee feeding on Spotted Knapweed

 

Male bee resting on Virginia Creeper
Male bee resting on Virginia Creeper

I have been collecting insects since 2005 and I collected almost anything unique to the eye. A majority of my collection was Coleoptera and Hymenoptera. In 2008, I started collecting native bees when I was using bowl traps for the Pennsylvania Department of Agriculture. My collecting was concentrated in Montgomery, Chester and Lehigh County.

Around this time the department was working on locating an invasive species by the name of Lithurgus chrysurus or the Mediterranean wood boring bee. The females cause damage to wood structures by burrowing into wood to nest. Overwintering of this bee occurs as prepupae inside a cocoon and they are univoltine, like numerous insects, where there is only one generation of brood in a year. This wood-boring bee was first found in PA in 2007. As soon as I heard about this bee I was intrigued and started looking for it. There are images to the right and above of the male, note the color variation.

After a few months of working I found this invasive species in my parent’s back yard and I discovered it on the biennial spotted knapweed. Ironically, spotted knapweed is also an invasive species and it produces chemicals that inhibit the growth of other plant species. This plant can cause quite a decline in biodiversity over time. I took many photographs and collected some specimens to make a positive identification on this bee and plant.

While observing the females I noticed they were very territorial and aggressive towards each other. There are some images below of some of the behavior I noticed. You can see in one image a bee that had been knocked down off the flower onto a leaf on its back.

Female collecting provisions on spotted Knapweed, note the full pollen load on the scopa of the underside of the abdomen.
Here a female is collecting provisions on spotted Knapweed, note the full pollen load on the scopa of the underside of the abdomen.
This Image demonstrates the aggressive nature of these females protecting their territory.
In this image you see the aggressive nature of these bees protecting their territory.
Here you see the aftermath of being knocked off a flower by another female.
Here you see the aftermath of a female being knocked off a flower onto its back.
Note the burnt red color on the T6 of this female, this is a key characteristic of this species
Note the burnt red color on the T6 of this female, this is a key characteristic of this species
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