Codling Moth: Biology and Ecology

Peter McGhee presents Codling Moth Biology and Ecology

Text Transcript with Description of Visuals

Audio	Visual
Hi, thanks for joining me today. I’m Peter McGhee, I work for Pacific Biocontrol, a company that sells pheromone mating disruption. I got my masters with Jay Bruner at  Washington State University working on stink bugs way back in the day, and then I moved to Michigan where I worked with Larry Gut at Michigan State University for 17 years in his research program helping him. Now I’m here to give you a little bit of background and refresher on codling moth biology and ecology.	Title slide. Presentation title: Codling moth Biology and Ecology. Author information: Peter McGhee PhD, Pacific Biocontrol
First, I’d like to take a little time to recognize the people that came before. A lot of our researchers are retiring, they all came on at about the same time and they’re all retiring at about the same time. Much of the information that you are going to hear throughout this codling moth summit was really generated from these people and more. So this doesn’t include everybody. These are people that have been really instrumental to the Pacific Northwest. Of course there’s Jay Brunner who spent his career here, a very basic researcher with a lot of applied information that he transitioned to growers. Vince Jones came along, he’s at Washington State University, recently retired and he’s done a tremendous amount on modeling and codling moth development. Don Thompson there with a mountain in the background, you know we wouldn’t have mating disruption probably at the level we do today for codling moths without his expertise in helping to develop this. And he worked with Jay Brunner and with Larry Gut who I’ll get to in a moment.	A slide displays a grid of portrait photographs showing eight scientists.
There’s Peter Vitskill out of Sweden, and although Peter didn’t work here in North America, he did a lot of the early research on pheromone communication and actually what’s happening out in the field with codling moth. The lower left there, there’s Larry Hull out of Penn State. Of course he was one of the icons of the industry, always had a really good program looking at efficacy of chemistries. Next to him is Larry Gut, who many of you know recently passed away due to stomach cancer and will miss him tremendously. Larry spent his career really advocating for tools that work for growers. He was really big with developing codling moth pheromone mating disruption with Don Thompson, Jay Brunner and others with the original camp programs and also moving that technology to the Midwest. There’s Gary Judd out of Canada, and Gary has been really instrumental in providing a lot of basic information on insect behavior and sterile insect technique and also with mating disruption. And lastly there’s Alan Knight who spent his year down in Yakima at the USDA and has always been looking at different lures and attractants and some of the basic biology of codling moth in general. All of these people have added to the wealth of knowledge that you’re going to hear over the next several days.
So today I’ll be covering codling moth, the pest history, the host ranges, basics about its biology and development, also some natural enemies that affect codling moth, and a lot about what are some natural susceptibilities for codling moth that are targets for management, and overall how the environment influences the their survival.	Slide titled “Agenda” contains a large drawing of a codling moth on the skin of an apple as well as a bullet point list outlining the 5 topics of the presentation as outlined in the audio.
So codling moth, as best as we know, came from the Kazakhstan steppe region. This is their natural habitat, it’s very much like Eastern Washington. It’s a rolling hill, lots of shrubs and scrub area with interspersed trees that are not always in large forested areas. They have pockets of apple, that’s where apple developed. Kazakhstan is famous for its national drink, fermented horse milk. Mmmm, that sounds wonderful and their enigmatic leader, Borat. Just kidding, and it’s also, if you didn’t know, it’s the largest landlocked country that has a Navy.	Slide titled “CM Native Range” contains a photo of the Kazakhstan steppe region which shows rolling hills, scrub brush, and snowy mountain peaks in the background. A bullet point list outlines that the Kazakhstan steppe is similar to eastern Washington, unforested, has interspersed trees, and has pockets of apple.
So there you can see Kazakhstan in green, the red circled areas are where codling moth is currently present globally. It’s spread to all of these areas through intense tree fruit production, and these areas include North America, Canada, US,  South America, South Africa, Australia, and New Zealand. And you know, really its original spread was westward into the main body of Europe.	Slide titled “Global Distribution” contains a map of the world in which Kazakhstan is colored in green. The areas listed as current range are circled in red.
Codling moth arrived in North America in the 1700s. Soon after that, in the middle 1800s is when we had Westward Expansion with the Homestead Act, the promise of free land and a new start to life. Many of these Westward homesteaders took apples with them and started their own small orchards. Other than water to make coffee and tea, or milk if they had a cow or oxen, there wasn’t a whole lot to drink. And cider provided a natural safe drink, slightly fermented cider wards off bacteria and fungi and so this was a staple on almost every homestead.	Slide titled “Westward ho!” contains a photo of a wagon train of settlers going through a desert-like landscape. A bullet point list highlights that codling moth was introduced to Eastern North America in the 1700’s and spread due to the Homestead Act in 1862. Another bullet point lists the beverages available to settlers including water, tea, coffee, milk, and cider.
Codling moth is a pest of several different fruits. As we know, it’s a pest of apple. It’s also a pest of pear. The knobby fruit that you see there in the top center, that’s a quince. I’ve never eaten a quince but codling moth has a fondness for quince. And also, of all the stone fruits, codling moth really likes apricots, so if you have apricots anywhere around any of your pom fruits these will likely have codling moth.	Slide titled “Hosts” which contains photos of apple, quince, apricot, and pear fruits.
Codling moth has a complete metamorphosis life cycle, and that means that they have distinct, different life stages. They have egg, larvae, pupa, and adult, so very distinct different life stages. It overwinters as a mature larvae in silken cocoon hibernacula, and that’s usually placed somewhere under orchard debris that’s at the base of the tree or somewhere in the cracks and crevices of the bark. In the spring, that larvae pupates, and after several days, the adult comes out. Males and females mate, and the female flies off and she lays eggs singly, anywhere from 60 to 90 eggs individually. And she’ll lay them on both leaves and fruit. Those eggs when they hatch, the larvae immediately find fruit to bore into. They tunnel their way into the center, eating the flesh and eventually getting to the seeds. Each of those life stages has sort of a set development rate, eggs are typically 6 to 12 days in duration. The larvae takes three to four weeks to develop, it spends 10 to 20 days as a pupa, and adults are generally one to two weeks old.	Slide titled “Biology” contains a diagram which illustrates the codling moth life cycle around an apple tree. Images show the eggs on fruit, larvae feeding inside apples, cocooned larvae on the tree trunk, pupae, and adult moths, arranged in a circular sequence indicating repeated generations. A bullet point list to the side summarized codling moth life stages with approximate durations.
Codling moth adults are just under a half an inch long. They have a gray body with this brown sort of speckling that goes over top on the four wings. They have these copper colored spots, these areas that are out towards the tips. And this particular family that codling moth is in, the Tortricids, they’re known for holding their wings in a tent-like sort of shape over their body. They also have these long slender antennae, and when it rests, they hold these back alongside of the body like you can see here.	Slide titled “Adults” contains multiple images of adult codling moths. Images include moths resting with wings folded tightly over the body in a tent-like shape, and one image with wings spread, showing patterned brown and grey forewings and coppery markings.
Females lay eggs singly like this on the undersides of leaves where they’re protected from both sun and from rain. They also lay them on the sides of fruit, typically from the stem bowl down to the calyx. In here you can see a caterpillar that’s just recently hatched out.	Slide titled “Strategic Oviposition” contains a photo of a single coding moth egg on the underside of a leaf as well as a photo of a recently hatched caterpillar on the surface of a fruit.
Females are capable of laying eggs all during the day or the night but really it’s a small window of activity. Typically between, you know, about three and seven PM that most of the oviposition happens, and then it continues up until midnight, but really it begins to drop off. And while they can lay throughout the rest of the day, most of it happens just during that three hour window later in the afternoon and early evening.	Slide titled “Temporal oviposition shows a line graph of codling moth egg laying over a 24 hour period. The x-axis is labeled “Hour” and the y-axis is labeled “Mean eggs per female per hour”. Egg-laying is low during the daytime and peaks sharply in the late afternoon, then continues to decline until midnight. To the right of the graph is a close up photograph of a codling moth egg on the surface of a leaf.
The hatched larvae develop through five different larval life stages called instars. Each time they shed their skin and they grow progressively larger and larger. All of this is carried out inside of the fruit, where they’re feeding on the flesh of the fruit making their way to the core so they can gain protein from the seeds.	Slide titled “Larvae” contains photographs of codling moth larvae at successive developmental stages, labelled first through fifth instar, increasing in size and changing in coloration.
Insects don’t generate their own heat like vertebrates do, we can shiver to stay warm, things like that. Insects development is really based on environmental temperature and that’s linked to enzyme activity. Enzymes work more quickly when the temperatures are higher and slowly when the temperatures are lower. Every life stage has an optimal developmental range temperature wise. And we can accumulate the number of degrees that are required for each of the life stages say the first instar, the second, third, fourth, fifth, all the way including the pupa and the adults. Generally a degree day is when the average temperature for the day is one degree above that developmental threshold for the insect, and for codling moth, that temperature, that bottom temperature, is 51 degrees Fahrenheit. So that means that one degree is accumulated for every degree over 51 for that day, and really their optimal range is somewhere between 50 degrees and 88 degrees on the high end. When it gets hotter than that, those enzymes aren’t nearly as efficient and so development slows down again. Well we can collect these degree days over time, and when approximately 250 degree days have been accumulated since an egg is laid, that’s when we can expect it to hatch. So by measuring and accumulating these degree days, we can predict different life stages for the insects and that in turn helps us to manage them in our crops.	Slide titled “Temperature Dependent Development” contains a simple graph with enzymatic activity on the y-axis and temperature on the x-axis. A bell shaped curve rises to a peak labeled “optimum temperature” and declines at higher temperatures. On the left, text explains degree day accumulation for codling moth development.
For each of these life stages, you can see the degree days that are associated with them. So for eggs to get from laying to hatch is 250 degree days. For 10 percent hatch, which is a good target for when we typically apply insecticide sprays targeting coddling moth, that’s about 350 degree days. For all of those larval stages to proceed through development, that takes about a total of 600 degree days. And that the time they spend as a pupa is about 514 or so degree days. In total, the life cycle of codling moth from egg through adult is about 1100 to 1200 degree days.	Slide titled “Temperature Dependent Development” contains a table comparing degree day to developmental stage. The columns are labeled “Accumulated Degree Days”, “Percent moth flight” and “Percent egg hatch”. On the left, text outlines the degree days associated with egg hatch, 10% hatch, larval stage, pupation, and total for life cycle.
Now I just talked about their development, but it really came out linear from egg, through larvae, pupa, adult, and then through the cycle again. But the reality is, there’s lots of individuals. This is all happening at the same time, so we actually wind up with overlap. We have adults that are flying and mating. They begin laying eggs, and even while they’re beginning to lay these eggs, over time we have some of those eggs hatching while some eggs are still being laid. We have larvae that are being developed, and larvae will go through their process and again, later in the season we see the whole process start over again.	Slide titled “Seasonal Phenology” shows a timeline of codling moth life stages across the growing season. The x-axis shows degree days aligned with months from April to August. Colored, overlapping curves represent life stages. Two major peaks indicate two generations, with adult activity occurring first, followed by egg hatch, and larval development.
So once the larvae that are in the fruit mature and they’re ready to go through to pupation, they don’t pupate in the fruit although some insects do. So where do they go? So that mature larvae, that fifth instar, they actually spin a silken thread just like a spider, and they slide down that from the tree, down to the orchard floor. And they seek out protected places that they can crawl under so that they can spin that silken cocoon. Typically that’s associated with bark that’s on the tree or, like I said, debris that’s on the orchard floor.	Slide titled “Where do they go?” contains three drawings. The first two depict the codling moth emerging from the fruit, and beginning to slide down their silken thread. The third drawing shows codling moths crawling into the bark of the tree in order to spin a cocoon.
So when those larvae’s spin that silk and they drop to the ground, this is the habitat that they used to be looking at. So trees typically were growing like this, standard self-supporting trees on an 8 or 10 foot spacing. And they really, these older trees tended to have rough bark, and this is where the mature larvae would crawl to and seek to find a place to spin that silk and be in that hibernacula for pupation.	Slide contains a photo of an apple orchard. The trees are large and mature, with rough bark seen at the base of each tree.
For many  years, going as far back as the 1800’s, growers used what we now call cardboard, corrugated cardboard. But they used strawboard, which was simply paper that had wheat straw that was glued to it, and these were wrapped around the trunk. Often times they would soak these with either pesticide or they would collect them and they would burn them later. They’re simply these convoluted areas they’re wrapped around the trunk of the tree. Today we use cardboard, as you can see here, there’s many larvae that are in hibernacula in that piece of cardboard, and also burlap has been used in the past.	Slide titled “Banding” shows three images illustrating codling moth banding. One image shows corrugated cardboard wrapped around the base of a tree. Another shows a piece of burlap tied with string around the base of a tree. The last is a close-up image of codling moth larvae attached to the inside of the corrugated cardboard. Bullet points on the left list banding use for density surveys, management, and biocontrol.
As we can see from this trellised orchard, which is much more representative of the apple industry today, we have a higher density of trees. They typically don’t grow nearly as large in diameters as those old standard trees, and they offer very little area for codling moth to find purchase and hide and form that hibernacula for them to pupate in. But you can see, there’s plenty of debris that’s at the base of the trees in that mound along the row and then we see the green vegetative strip.	A wide shot image shows trellised orchard rows, supported by wooden posts and wires, stretching across a hillside. Brown debris is visible at the base of the trees.
So I like to think of codling moth as survival of the hiddest. They’re masters of finding nooks and crannies and places to form that hibernacula and eventually pupate. Whether it’s on the tree or in the ground cover, they’ll find that place. great study done by David Epstein when he was in Michigan found that a large portion of codling moth could be found during the daytime in the ground cover, in that green vegetative strip, and that’s because it has a higher relative humidity than the canopy itself. And places like the Pacific Northwest, where fruit’s grown in eastern arid Washington, you can imagine that any place that has higher humidity is where you’re going to find those codling moths.	Slide titled “Survival of the hiddest” contains a photo of an apple orchard with mature fruit on the trees. A bullet point list on the lift outlines that codling moth adults can be found in the tree canopy and ground cover, that mating disruption moves females up and males down in the canopy, and that heat moves adults into ground cover.
And I think you’ll hear more about these things later in other talks, but codling moths are real good opportunists. So if there’s bin piles that are around, they’ll find their way to the bin piles. Here you can see a bin pile full of cut apple wood that’s likely going to be sold for firewood. In my experience in Michigan, we tried to collect codling moth larvae for studies and we filled bins with wormy fruit, and we lined the inside of that with corrugated cardboard, and came back to collect the larvae from that corrugated cardboard, and found very  few. And it turns out that codling moth preferred to form their silken cocoons on the underside of the bins on the skids where they interacted with the ground. We found hundreds and thousands of them in that location. So even though they will get into and on bins, they’re even known to get into plastic bins, they prefer to be on the underside. In my experience, that’s what I’ve found. When you have feral apple trees or backyard trees with fallen fruit that lays on the ground, this is a prime source for codling moth to just keep building and generating over and over and over again. So cleaning up the fallen fruit and even the leaves that have fallen at the end of the season is a good strategy for managing the population.	Slide titled “Opportunists” contains three photos representing practices that can lead to codling moth proliferation. The first is an apple tree growing alone in a field. It appears unmaintained and has dropped fruit to the ground. The second image is of apples which have dropped to the ground of an orchard. The third image is of wooden bins of cut apple wood lined up outside an orchard.
Codling moth, just like any other living organism, has things that are natural enemies. There’s microbes including viruses and bacteria, nosema, fungi, and even nematodes that attack codling moth. There’s also other invertebrates, so beetles, spiders, earwigs. There’s several egg parasitoids that attack them. Of all the groups you can see in the study by Unruh et al., really earwigs and ground beetles, carabids, they tend to make up the most of the natural predators from that invertebrate category. When we think about vertebrates, there’s really not a whole lot except for birds. Although, woodpeckers like this northern flicker are really good controls for codling moth. And in fact, when I showed you the pictures previously about banding with cardboard, I have an organic friend in Michigan that bands all of his trees every year. And because he’s done it for so long, the birds have gotten smart and they visit all of those cardboard bands. And they just peck through the bands, which is very easy and they remove all of the larvae. He’s got more woodpeckers in his orchards then you could shake a stick at. I don’t even know that he collects the bands after the end of the season to destroy those codling moths, the birds do such an effective job.	Slide titled “Natural Enemies” shows a bar chart comparing different predator groups associated with codling moths. Small photos of insects and spiders appear next to the chart. Additional images show a woodpecker on a tree trunk and a codling moth in the core of an apple.
Okay so we’ve made it to this part of the movie now it’s time to talk about sex. So codling moth spends most of its life preparing for adulthood, and it has actually a very short life as an adult. Oftentimes they don’t even feed as adults, and if they do it’s usually just on nectar sources. But they don’t need any food as an adult to survive and reproduce. So the one driving force that motivates them is reproduction. How do they find each other? Well there’s no bars, no, you know, high school or college house parties, there’s no office romances. So they need to get together, and they have a built-in mechanism for that.	Slide contains a cartoon drawing of two moths talking to each other. A text bubble above the first moth says “I think you’re really cute”. A text bubble above the second moth says “OMG”. Text to the right of this image says “Let’s talk about SEX…”
As I said before, females typically are located in the upper part of the canopy.	Slide titled “Pheromone communication” contains an image of a cartoon apple tree. A female codling moth is seen in the upper right corner of the canopy.
And females produce a sex pheromone. It’s like a perfume, and they emit this in the evening. And she puts out this pheromone trail, as you can see here from these lines.	Curling lines appear from the female codling moth representing pheromone trails.
And males fly along, and their antennae comes into contact with these odors. And when they find that, they fly up the source, that concentration gradient, until they find the female. They really rely on odor as their way of getting together and less so much on visual cues like humans do.	A male codling moth flutters onto screen and along the pheromone trails until it reaches the female codling moth in the canopy.
So in the big picture of things, how far are you willing to travel for sex? For codling moth, it’s probably further than you think. But in reality, it’s a lot less than what they actually do. So males typically travel anywhere from 100 feet to up to a half a mile, but generally most of their activity occurs in less than a quarter of a mile radius. For the females, we know that virgin females, those that aren’t mated yet, they tend to fly further than females that have been mated. And that makes sense, because they’re out looking for a way to find a new area, to go find a boyfriend, to get mated, and to lay eggs. If you’re already mated and she’s ready to lay eggs, there’s no need for her to fly all over the world to just drop eggs here and there. Mated females, ninety percent of them travel less than a quarter of a mile. There are long distance flyers. So there’s genetically dispositioned codling moths that are different than the rest of the population, and we know that they’re capable of flying over three miles. So not all codling moths do that, but this would be a way that they enhance and spread their genetics and spread out to other areas. This goes back to the area that they originally came from, where I said they had apple trees, but they weren’t in orchards. They were, you know, a couple of apple trees here, and then great distances before the next cluster of apple trees where you would find a food source. When females fly great distances, it’s been shown that they have reduced egg production. So their fecundity goes down, and whether that’s because they’ve expended a lot of energy flying, or simply because it’s taken them so long in their lifespan to do that isn’t known. But those long distance flyers tend to lay fewer eggs.	Slide contains a drawing of the earth with colored branching lines connecting different places on the map. Text overlayed on the map says “How far are you willing to travel for sex”. Text to the right of the map says “Further than you think, but in reality, less means more sex”.
So females produce this magic elixir, the sex pheromone that draws males to them so that they can mate and lay eggs. They produce this on demand and it’s driven by the daylight cycle. So as daylight begins to wane in the evening, they begin pheromone production about two hours before sunset. Maximum production is reached within two hours after sunset and it continues for just a few hours. And that’s the peak calling period, its usually within three to four hours after sunset. The reason that they likely produce this on demand is it’s very energy expensive. They can’t spend all day just burning energy to produce this pheromone, and also pheromones are volatiles and they release fairly easily.	Slide titled “Temporal Pheromone Production and Emission” contains a clock graphic on the left and two bar charts on the right. The charts illustrate pheromone production and release by female codling moths over time, comparing a group of 10 females as well as individual females. Text on the slide notes that pheromone production is short lived and peaks a few hours after initiation.
There have been many studies done on the effect of temperature on codling moth development and also their activity level. In a study that was done in Michigan where male codling moths were taken to an orchard and there was a field flight tunnel that was set up and pheromone was put at one end and the males were flown to that pheromone continuously. This was done over about a 2 week period, and what was found through this study is there is a critical temperature where males, although they can be active, they’re really unable for flight activity to fly to that pheromone source, and that is right around 58 to 60 degrees. So you can see on this figure where, anytime you see those blue dots that are above 60 degrees, that was 41 percent of the moths were able to respond. And on nights where it was below that, you can see we had very little response, zero or four percent. And so evening temperatures can be a really good predictor of how much codling moth activity you’re going to find. The ideal flight temperature is somewhere between 80 and 90 degrees for codling moth. So during that window is when you’ll find the maximum amount of activity. When you go above 91 degrees, you’ll still see flight, you can catch them in traps, but you’ll see a decrease in the amount of overall activity.	Slide titled “Impact of Temperature on male (female) activity” contains a scatterplot of male moth flight activity over a period of 13 days. Percentages above the data indicate the proportion of moths flying to the pheromone at different temperatures. A horizontal line across the graph at 60 degrees Fahrenheit denotes the flight threshold and periods of low activity are highlighted at cooler temperatures. To the right of this is a cartoon graphic of two thermometers, one that is very cold and has icicles hanging off of it, and one that is very hot and is sweating.
So cold temperatures can reduce the amount of adult activity during the summer, but what about in the winter? What does cold do to the insect? Codling moth is classified as a freeze intolerant organism, but it’s one of the most cold tolerant pests that we have. So freeze intolerant means that some insects can actually freeze solid and then they can reanimate after being frozen entirely. Codling moth can’t necessarily do that. When ice forms inside the cells it kills them. So they’re considered freeze intolerant, but they have mechanisms where they can super cool their body and they can survive temperatures that are actually below the freezing temperature of water.	Slide contains two photos of winter orchard, one is a shot of an orchard on a hillside with snow covering the ground and the branches of the trees. The other image is a close up of ice covering the limb of a tree. Text on screen says “…Baby it’s cold outside”.
There have been a number of studies conducted looking at this super cooling and freeze intolerance with codling moth. This is just one figure to give you an idea of how cold tolerant these insects really are. You can see along the bottom, there’s feeding larvae, there’s one to two day old cocooned larvae’s, they’ve been spun up in their hibernacula for one to two days. Then there’s some that have been there for three to five days. Or if they’ve been in that cocoon for longer than five days and they were exposed to these super cooling temperatures, you can see that their survival is greater at lower and lower temperatures the longer that they’ve been in that hibernacula and become acclimatized to that cold temperature. Generally codling moth use trehalose and glycol within their body fluids that helps to allow them to super cool. They’re able to survive easily in temperatures down to minus four degrees Fahrenheit for extended periods of time, and also snowpack and things like that act as an insulator. So while the outside air temperature might be below zero, it might be minus four degrees or minus 10 degrees. Where they have chosen to spin their hibernacula might be protected from that ambient air temperature by other means as well.	Slide titled “Supercooling and Freeze intolerance” shows a box and whisker plot of supercooling temperatures, measured in degrees Celsius, across 5 different codling moth development stages. Feeding larvae have higher supercooling points, while cocooned larvae and pupae tolerate progressively lower temperatures as they acclimatize.
Well what about the converse? Does heat affect them? So let’s turn up the heat like we did last summer when we had over 115 degrees Fahrenheit in the field? Can cooking them at these temperatures reduce the populations? And the answer is: sorry, probably no. We don’t actually have great field data from studies on this, but what it looks like from studies that were done on how to kill codling moth for quarantine issues after the apples have been harvested. So you know, potentially if there’s codling moth caterpillars that are in the bins and things like that, we know from these studies that these insects can survive temperatures up over 118 degrees for a good period of time. And so it doesn’t look like field temperatures are ever going to be hot enough to reduce the population significantly.	Slide titled “Let’s turn up the HEAT!” contains a graph with of exposure time versus temperature. As temperature increases from approximately 115 to 126 degrees Fahrenheit, the time required to affect codling moths decreases, but the results indicate that high temperatures alone are not sufficient for effective control.
There is good news though, the environment can have a negative impact on codling moths. So what’s the influence of things like wind and rain on their activity? Male catch is greatest when the wind is somewhere between one and three miles per hour. It’s a very narrow window. If it’s below one mile per hour, there’s not enough wind to pull that pheromone plume from the female and draw it out linearly so that he can follow that up the concentration gradient. So air that’s too still is not good. And also, air that’s over three miles per hour is just too strong. It breaks up that pheromone plume so that it’s very challenging for the male to find the female. We also know that moisture, anytime we have rain that’s over about a tenth of an inch within eight hours, it shuts down flight for that entire evening so is there a way to use water and irrigation to reduce the amount of male flight where they’re looking for females that’s always a possibility.	Slide titled “Influence of Wind and Rain on CM activity” shows and illustration of a tree bending in the wind and a rain cloud. The slide summarizes that light wind supports moth flight, while stronger wind and rainfall suppress flight and trap catch.
Insects in general are fairly short-lived creatures and codling moth as an adult is fairly short-lived. Adults are typically around for one to two weeks until they die. Good study by Jones and Wyman showed that, and since they’re so short-lived, every evening really counts. By delaying when a female becomes mated, she’s not mated on that first evening, she doesn’t find a boyfriend until night three or four like the yellow bar, the amount of viable offspring that she’s going to produce decreases. So if we can keep females from becoming mated for four to five or six days, just the age, that she’s that much older reduces the amount of eggs that she’s going to be able to lay that hatch into larvae.	Slide titled “Effect of Delayed Female Mating on Fecundity” contains a bar graph of female age when mated versus the number of viable offspring per female. There is a sharp decline in the number of viable offspring for each progressive age category.
Codling moth can be one of its own worst enemies, and that I’m really just kind of kidding with. It’s interesting, females lay eggs individually on fruit and leaves. They might lay some eggs that are close together and you can find fruits that are damaged by more than one larvae. Codling moth larvae are cannibalistic. They’re trying to get to the center of the fruit where the seeds are so they can eat those seeds and they get protein from that. And while the fruit can probably support a larger number of larvae, they’re actually cannibalistic, and if they find another larvae in there they’ll attack each other and kill each other off. Here you can see a study that was done in 2019. And most of the apples that have just one larvae, that their success their survival rate is up above 90 percent. The more larvae that are found in an apple, survival rates go down for everybody at that point.	Slide titled “Sibling Rivalry” contains a bar graph of survival rates of larval development versus the number of larvae per apple. There is a sharp decline in the percentage of survival for each successive larva that is added, with the sharpest decline seen between the 1 larvae per apple and 3 larvae per apple groups. Above the graph there is an image of an apple with multiple codling moth holes in the surface of the fruit.
Lastly I think it’s really important to point out other species that are similar to codling moth. Oriental fruit moth, while it’s not a widespread pest in the Pacific Northwest, it is in other apple growing regions. And here you can see codling moth next to oriental fruit moth. Codling moth, like I said, is just under half an inch in length. Oriental fruit moth is a real tiny, about a third of an inch in length, moth and it’s really a dark gray appearance. You can see down here where they’re compared here, oriental fruit moths about a third of the size of codling moth. So adults they’re fairly easy to determine from one another, and you can find them in each other’s monitoring traps. It’s easy to get cross-contamination and you often will find oriental fruit moth in codling moth traps if they’re in the area.	A comparison slide labeled “CM” and “OFM” shows adult codling moths and oriental fruit moths side by side. Codling moths appear larger and with copper-colored patches near the wing tips, while oriental fruit moths are smaller, narrower, and more uniformly grey.
As larvae they’re much more difficult to tell apart simply because they’re so small, but they do have a difference on their butt. If you look at coddling moth larvae they do not have on the last segment what we call an anal comb. Oriental fruit moth does have this sclerotized toothed anal comb. In studies on other insects that had this type of device, this has actually been seen to flick their poop away from where they’re feeding so that it doesn’t likely draw parasitoids to come and attack them.	A comparison slide titled “CM / OFM Larval Identification” shows the posterior ends of two larvae. On the right, the oriental fruit moth larvae have a visible anal comb made up of several small tooth-like projections. On the left, the codling moth larvae lacks this anal comb.
They all also have slightly different feeding characteristics, and at first glance it probably doesn’t seem to be different, but after seeing these two pests repeatedly time and time again you do find some differences. Where they enter the fruit, codling moth typically enters the fruit along the side, so anywhere around here. And you can see, this tunnel comes into the side and the tunnel goes pretty straight directly to the seeds inside the carpal. They want those seeds, and that’s where they’re going. Also you rarely find fruits that are stung or entered more than once unless they’re clustered together or if you have a severe high infestation. That might be near an abandoned orchard or bin piles or something like that. You’ll always find these brownish sawdust areas outside of both codling moth tunnels and oriental fruit moth tunnels, and that’s their frass, that’s their poop and it’s loosely held together with silk that they spin.	A slide titled “Codling moth” shows two images of damaged apple fruit. On the left, a cut apple reveals internal tunneling caused by the codling moth larvae feeding towards the seeds. On the right, an intact apple shows a pile of brown frass at the entry hole on the side of the fruit.
Now oriental fruit moth, on the other hand, is really a shoot feeder. So they burrow their way down into shoots, and you can see a larvae here, and they tunnel their way directly in. They push their frass out, and this is where you typically find oriental fruit moth, especially with stone fruits. You do find them with pome fruits in these areas as well. And when the leaves die and they fall over, we call that terminal flagging, and it’s an easy way to find if you have an oriental fruit moth infestation.	A slide titled “Oriental Fruit moth” contains two photos of oriental fruit moth damage. On the left, an oriental fruit moth is seen tunneling through the shoot of the plant. A small pile of frass is seen at the beginning of the tunnel. On the right, dead, fallen over leaves are seen on a shoot, indicating terminal flagging.
Now when they attack fruit, it’s slightly different than codling moth. They love to enter fruits from the calyx end, that’s where you’ll often find this frass collecting at the bottom of the apple. So that’s their favorite point of entry for apples. Also they tend to have this more serpentine tunnel. It goes in from the calyx and it circles around the seeds and they never really go into the core to feed on those seeds. They can but they rarely do it, and also codling moth sometimes doesn’t feed on the seeds but predominantly that’s what you’ll find.	Slide titled “Oriental Fruit moth” contains two photos of oriental fruit moth damage on apples. On the left, an oriental fruit moth tunnel is seen on the calyx end of a small growing apple, a pile of brown frass sits on the surface of the fruit. On the right, a cut apple shows internal tunneling caused by the oriental fruit moth larvae. The tunnel goes around the seeds and they are left untouched.
So in closing, let’s wrap up some of the major things that we learned. Codling moth as we know, is primarily an internal feeder. It’s the primary internal feeder that we have. And in the Pacific Northwest we have generally two to three generations per year. The larvae are exposed to the environment for a very short period of time. That egg that’s laid on the fruit, they exit the egg and they burrow directly into the fruit, usually within an inch of where that egg was laid. They have few natural enemies although they do exist. And we also learned that they’re very weather hardy.	Slide titled “Summary” contains a bullet point list summarizing the main points of the talk, as outlined in the audio. To the right of the list is an illustration of a codling moth adult sitting on a leaf while a codling moth larvae exits the fruit along a silken thread.
Also we learned adults are active from sunset till about midnight, we see very little flight that’s happening in the morning. Although occasionally you can see some male flight in the morning, but females don’t call after midnight. It’s been shown that they shut down their pheromone production and that’s all you get. Temperature wise, adults are not active below 58 to 60 degrees and most of that activity, flight activity for adults happens between 80 degrees and 90 degrees. If you had rain during the day and it was, you know, a somewhat significant rain event that had a tenth of an inch of rain or so, adults won’t be active for that day. Also any sort of wind that’s over three miles per hour or if it’s just stagnant, stand still wind, you’re not going to have adults flying then. And lastly we learned that delayed mating for females really reduces the amount of viable offspring that they’ll have. Well I hope this was a good refresher and maybe you learned one or two new things. There’s a lot more talks to come and I hope that you enjoy the sessions after this, Thank you.	Slide titled “Summary” contains a bullet point list continuing to summarize the main points of the talk, as outlined in the audio. To the right of the list is a picture of apples growing on a tree.
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