The Daily Bucket is a regular feature of the Backyard Science group.  It is a place to note of any observations you have made of the world around you.  Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket.  Please let us know what is going on around you in a comment.  Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
Autumn, 2013                                                                           Pacific Northwest

Ripe fruit is an irresistible source of concentrated sweetness in nature. If we humans don't get to the fruit trees and bushes we've planted soon enough, there are plenty of wild critters who will. For us it's a tasty healthy treat, for them it's pure energy to fuel growth, reproduction and overwintering.

After getting stung by a Yellowjacket last summer, I became very cautious and watchful in all my doings outdoors from then on. We had a particularly bad Yellowjacket season this year because our spring was mild and dry, unlike the last two springs. I'd forgotten how aggressive they can be in the later part of the season! Besides donning full-body protection to pick fruit, I also started paying closer attention to who else was enjoying my blackberries, pears, raspberries, figs and apples. As I watched, I noticed there were changes in the foraging insect populations.

Since Backyard Science is about noting changes in nature, I decided to document the shifting in fruit foragers as the cool of autumn approached. This is what I saw, with identifications as close as I'm able to make.

(more critters and ripe fruit below....)

The blackberries were consumed or withered soon after the photo above, at the end of September. But the figs were just ripening. Here's the sequence between September 30 and October 15. Note: the figs were in all stages of ripening, and the photos were taken at different figs. The insects were similar at any fig being foraged.

First insects noticed: Fruit Flies (Drosophila sp.), with some Yellowjackets (Vespula sp.):

A few days later, still Fruit Flies present, but now there are lots of the red-eyed Small House Fly (Fannia sp.), as well as more Yellowjackets:
A few days later, still Yellowjackets and Fruit Flies, but now we have lots of Blue Bottle Flies (Calliphora vomitoria)
By the second week of October, the Yellowjackets became very numerous. Still some Fruit Flies and Blue Bottles:
During the second week, the figs also began to mold. Here are insects continuing to eat the inside of a fungus-covered fig:
By the 18th, the figs were either picked by me, or consumed and moldy:
I know insect activity is highly influenced by weather, and its larger picture, climate. Global climate change can already be measured biologically.
Global climatic changes are expected to impact insect-plant interactions in several ways. They might affect insects directly, through changes in physiology, behavior and life history parameters, as well as indirectly, through changes experienced by host plants in their morphology (Barnes et al 1988, Morrison & Morecroft 2006, Lake & Wade 2009), biochemistry (e.g., Yuan et al 2009), physiology (Gifford et al 1996, Yadugiri 2010) and patterns of richness, diversity and abundance (Thuiller et al 2005, Kazakis et al 2007). Insects play important roles in ecosystem services, acting as herbivores, pollinators, predators and parasitoids, and changes in their abundance and diversity have the potential to alter the services they provide (Hillstrom & Lindroth 2008). The number of studies reporting climate change effects on insects has rapidly increased during the past 20 years.
(Climate change and its effects on terrestrial insects and herbivory patterns. T Cornelissen, Depto de Engenharia de Biossistemas, Univ Federal de São João Del Rei, São João Del Rei, MG, Brasil)
It is yet to be seen what effects we will see in the U.S. Pacific Northwest, although models provide predictions.

As a possible explanation for the changes in insect activity I've been seeing this fall, I looked at the temperatures we have experienced. This data comes from Wunderground, the blue lines historical average high and low temperatures, and the red line the actual temperatures this year. September temps were very mild compared to average values for this area.

sept 13
Temps September 2013 Friday Harbor, WA
October temps started mild and then dropped below average on the 4th, becoming mild again for a week, and then getting normal or slightly cooler nights than usual again for the next week, until the 19th. After that it warmed up again. Could the end of the Yellowjackets in the third week of October have been caused by the cool temps the week before? I don't know. This is my first year documenting dates of the comings and goings of nature events, so these observations will be my baseline in comparing future fall insect activity. There are other variables besides temperature to consider as well, such as precipitation, light, wind.
Temps October 2013 Friday Harbor, WA
By a week ago, there were no insects on the few remaining figs, which are now rotting away by fungal and bacterial activity. But I've also been watching the pears as they have been falling since the end of September. This has been a tremendously productive year for my two pear trees, and at the rate I'm able to process them (mostly dehydrating for winter treats), I didn't want to collect all of them at once. So each day I've collected the fallen intact pears, and left the split ones for the insects. This is the activity I've seen in the pears since the end of September.

First, the flesh was covered with Fruit Flies, and a few Yellowjackets:

In the first week of October, the Fruit Flies and Yellowjackets were joined by Bald-Faced Hornets (Dolichovespula maculate):
and slugs. This is one of our invasive European species:
The second week of October was very busy with Yellowjackets. During this time I was able to pick up nearby pears without the YJs seeming to notice or care:
Blue Bottle and Small House flies, as well as Hornets also present through the second week of October:
By the 21st of October, there were no Yellowjackets or Hornets at all. I did not note on exactly which day that happened - it's harder to pay attention to when things are LAST seen, compared to when they are FIRST seen, since we are actively watching for FOS ("first of season"). The Fruit Flies were still abundant though:
The population trends are fairly similar between the fig and pears, although I didn't see Hornets in the figs. The Fruit Flies started earlier and lasted longer than other insects on both fruits. Considering how ubiquitous the Yellowjackets had been all year, it was a real surprise to find them suddenly absent, everywhere. I'm sure the Queens are safely ensconced somewhere for the winter, many of them likely in my woodpile.

Our seasonal changes in the Pacific Northwest are pretty moderate compared to most of the country. Here it is nearly the end of October and it hasn't gotten cold yet (average first frost is middle of November). I expect you see more dramatic changes in insect activity than I do. What weather factors do you notice around the end of Yellowjacket season where you live, if you have them? What other kinds of insects do you see scavenging ripe and rotting fruit? It would be interesting to compare our experiences.


The Bucket is open for any nature observations from your backyard. What are you seeing as autumn progresses in the way of plant or animal activity?

And remember -

"Green Diary Rescue" is Back!

"Green Diary Rescue" will be posted every Saturday at 1:00 pm Pacific Time on the Daily Kos front page.  Be sure to recommend and comment in the diary.


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