Growing Degree-Days for Everyone

For, lo, the winter is past, the rain is over and gone; the flowers appear on the earth; the time of the singing of birds is come, and the voice of the turtle is heard in our land. KJV Song Sol. 2:11—12

It’s time to spray for insects.

Your schedule depends on how warm the weather is, which can be measured with a backyard weather station. The data extracted from the station drives models of insect development that predict when sprays will be most effective.

The models are expressed in cumulative Growing Degree-Days, which are not your grandfather’s Cooling Degreee-Days. These models have different temperature thresholds, different starting points, different kinds of temperature cutoffs, and different ways of approximating diurnal temperatures. You need automation to use the models.

I have an Ambient Weather WS-2095 Wireless Home Weather Station. I use the WeeWX free, open source software package that runs on Linux and Macintosh computers to handle the data.

This announces Phenology, an update to my WeeWX extension that calculates insect development stages. It is a collection of Python 3 scripts. It has been tested with WeeWX 4.2.0 and 4.4.0.

WeeWX Users may download the “tarball” from:

For the mildly interested, complete and utter documentation is at:

Many insect models are supported, including several for the following species:

  • Apple Maggot
  • Codling Moth
  • Corn Leaf Aphid
  • Leafrollers
  • Gypsy Moth
  • Green Peach Aphid
  • Oriental Fruit Moth
  • Peachtree Borer
  • San Jose Scale
  • Squash Bug
  • and many, many more…

In the wake of the Plague, folks are turning to backyard gardening and orcharding in droves for the benefits of social distance and to reduce reliance on commercial food sources. Some even hope to save money by growing their own. :smirk: They’re building up immunity in the sunlight and fresh air, too, maybe.

If you’re thinking about doing the same, now’s the time to secure sources of plant materials, gardening and preservation supplies, and agricultural chemicals because these things have been and will continue to be in short supply.

Quick! Before evenings get too short, start boning up on how to begin this season with resolve.


I know only one turtle who talks. This guy:image

But I am thinking you meant “turtledove,” which is this guy, right? image

Thanks for the spray timing info. Something to look into for sure.


I’m always uplifted when I see a turtle dove at my house. There’s something beautiful, even magical about them.


I personally love the sounds of rock doves,


I’m always glad to see pairs of geese flying down the creek in the mornings–towards the lake–along with the less frequent heron, and then seeing them return in the evening back towards their marsh (next door to us). That’s when I know spring has arrived.

Art songs are terra incognita to me. Apparently there are German art songs as well as French art songs. Here’s an example of absinthe-fueled lyrics to one of the latter from the fin de siècle:

L’ombre des arbres (The Shadow of Trees)
Paul Verlaine

The shadow of trees on the mist-drenched river
Dissolves like vapour
While in air, among the true branches flown,
The turtledoves moan.

How this pale land, oh traveller, too
Pale yourself, mirrors you,
And your drowned hopes. How sadly they weep
High in the sighing leaves!


You can hear this as lyrics to the art song by Claude Debussy, recorded in 1904 and accompanied by the composer. The piano score is famous for capturing the dissonant song of the turtle (doves).

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