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Sustained catch in Chemung County

Both sites in Chemung County are now at sustained catch. During the week ending July 27, 2018, 4 males were caught at one site with a raspberry and a blueberry planting, and 6 males and 2 females were caught at the other site in a blueberry planting. These sites are being monitored by Shona Ort, Chemung County Cornell Cooperative Extension.

Insecticide programs are in place now, which will suppress SWD population growth within the planting. In unmanaged locations, SWD numbers will continue increasing as approximately 10 generations of the insect develop during summer and early fall. A recap:

  • SWD monitoring, fruit.cornell.edu/spottedwing/monitoring/ – describes what you can do.
  • SWD management, fruit.cornell.edu/spottedwing/management/ – describes what you should do.
  • SWD distribution, fruit.cornell.edu/spottedwing/distribution/ – describes where the CCE network is finding it.

Remember, the short life cycle and 10+ generations per year will make for high pressure situations in a few weeks’ time. Management, management, management…

Why does the SWD population explode?
You can do the math. Let’s think optimum conditions for SWD development. A single female can lay around 350 eggs during her lifetime, about 15 per day. The egg to adult phase of the life cycle takes as little as 6 days. So, one female in one day can result in 15 more adults 6 days later, and, during those 6 days, she will have laid another 90 eggs. 6 days after that, those 90 eggs will all be adults. Half of the 105 adults will be females, capable of laying ~350 eggs during their lifetimes…that’s 18,375 eggs or 9,187 females in about two weeks.

Meet and greet – male (right) and female (left) SWD – on a raspberry fruit.

A typical life span for SWD is 3 to 9 weeks and there are estimated to be about 10 generations per year in the US, depending on climate. Back to the one female. Let’s say that she lays 70 eggs per week and, when she dies in 5 weeks she’s laid 350 eggs and, by then, about 280 of those are adults. Half of those adults, 140, are females and, by then, have laid 49,000 eggs, 29,400 of which will, by then, be adults. Half of those adults, 14,700 are females and, by then, have laid 3,087,000 eggs …I’m lost and I probably made a mistake…but you get the idea – over 3 MILLION in five weeks from ONE (really from two, because you need a male and a female).

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