|Brood Emergence Timeline|
So what can a gardener expect? Fortunately, Cicada's have no functioning mouth parts capable of chewing a plant to pieces it does feed like an aphid on a plants sap. We don't need to think of them as a swarm of locust that will blot out the sun and lay crops to waste. These clumsy flying machines are only concerned with finding a mate, having sex and laying eggs. The last stage of laying eggs is where we can expect the most damage as the female splits the bark of small branches and lays anywhere from 600 to 800 eggs in the wound before she dies. Once the eggs mature, the nymphs hatch and fall back to the ground, disappearing for another 17 years. Although trees with significant damage from the egg laying process will invariably loose tips from branches, one shouldn't despair as trees quickly recover. It's nothing more than the Cicada's Barbers shop for trees, just taking a little off the back and sides.
So what benefit can come from all these Cicada's waking at the same time? After all, events like this don't happen in nature without some kind of reason. As it turns out, a researcher who studied the 2004 Brood X emergence found some positive repercussion following that outbreak.
It was discovered in the years following the 2004 outbreak, that there was an increase in plant growth stimulated from damage that had occurred by the Cicada's. Also, as the larvae tunneled through the soil, it helped aerate the soil around the plants roots. This tunneling reduced compaction of the soil and allowed moisture from rain or sprinklers to penetrated deeper into the soil. Lastly, the dying bodies of Cicada's actually became a great source of fertilizer. As their bodies decay, it provided a valuable source of nitrogen and other nutrients that plants re-absorb.
Scientist refer to this occurrence as a 'Resource Pulse'. It is a term given to a large magnitude, but short interval and infrequent event where an resource availability was increased. The study showed that plants given a diet of decaying Cicada's produced seed 9% larger than non-insect fed plants. It's possible that a single acre of forest can yield up to 1 1/2 tons of nutrient rich dead bug carcass. Those nutrients end up pouring back down the millions of finger sized holes in the ground from where they emerged. In someways they return back to where they came from.
|Cicada Killer in action|
Flickr.com - Dendroica cerulea