oak lecanium scale insects are the honeydew rain-makers I wrote about in my last post. This spring these scale insects have been busily feeding on the tree's sap and dropping honeydew droplets over everything on the forest floor.
Here is a photo of the oak lecanium scale, warty and blister-like, on some oak branches.
Scale insects do not look very much like insects, do they? They would pass for small bumps on the branches, or small galls, or even some kind of fungus rather than insects.
I flipped over a scale insect to show its underside. It is not much to see, but the underside does look more insect-like than their nondescript shield-like topside.
All of the eggs pictured below are from one scale insect!
Would you like to see something even more incredible than such a vast amount of eggs?
On about every third branch, or so, I could see some tiny parasitoid wasps laying eggs on the scale insects. These wasps are biological control agents aligned against the scale insects. They are charged with a daunting task, eh?
There were a few species of these tiny wasps actively laying eggs on the scale insects. Here is a close-up photo of one of the minute wasps I found crawling among the Oak lecanium scales.
These little wasps aren't alone in their battle against the Oak lecanium scale insects.
Here are some other natural enemies of the scales that have joined the battle.
Here is possibly another enemy of the scales. This small, two-spotted black lady beetle is, perhaps, one of the Hyperaspis species. I noticed a number of these black-colored lady beetles crawling on the Oak lecanium scales. I assume their larvae prey on the scale insect eggs... see below.
I also observed some light-colored larvae that were covered with downy white wax crawling among the scale insects. Some of the beetle larvae had a powder-coat of wax while others were rather hairy with wax tufts. I believe these are larvae of lady beetles similar to the adult lady beetle in the photo above.
As I was peeling off some scale insects, I occasionally found some wax-covered beetle larvae living beneath the scales. Obviously these larvae were feeding on the scale insect eggs.
I poured out the eggs of one scale and this little white larva tumbled out with the eggs. Again, I suspect it is a larva from the ladybird beetle family probably Hyperaspis sp. Notice how the larva has the beginnings of tufts of white wax.
I saw more biological control agents busy battling the scale insect infestation. For example, I saw some very small syrphid flies dive-bombing the scale insects. They would hover nearby then drop in for a quick contact -- which I assumed was to deposit an egg.
The honey-dew rain is almost over... for now. This batch of scale insects have mostly sucked their last sap. Now they are full of eggs... remember my photos of all those eggs that poured forth when I peeled off one scale insect? Think about each one of these bumps on a branch containing, what, thousands of eggs? Can you imagine what it will be like when all those eggs hatch?
Which side is going to win the battle? Are the scale insects going to increase a thousand fold next summer, or will their natural enemies be able to keep them under control? Will the bio-control agents bust up the bivouac on the branches enough that next year the scales will less of a factor in the forest and thus escape attention from the outdoor folks?
I'll keep tabs on these scale insects and their enemies and I'll post more about them later on this summer.