How to setup monitoring traps for tree fruit insect pests, like codling moth

Each spring, I know some of you may be using insect-pest monitoring traps for the first time, whether it’s in your orchard or backyard! It’s exciting to have these tools – they do the work for you, luring insects into a single location so you don’t have to guess when pests might appear. Moreover, you can use trap counts to inform your decision to take action at the best time to protect your fruits. With all this said, it can a little stressful, or even overwhelming, to setup these traps if you haven’t used them before or don’t have someone close by to ask. So, in this article, I will share some tips for when and where to place insect monitoring traps, and I’ll use codling moth as an example, since it’s a key tree fruit pest that can be detected easily and reliably with pheromone-baited traps!

Codling moth, also known as the classic “worm in the apple” is an important apple pest to manage. The caterpillars (Figure 1) are the actual damaging life stage, burrowing into apples to feed and destroying the fruit in the process. However, the caterpillars won’t appear until later in the growing season, so management efforts are focused on the adult moths (Figure 2). By using monitoring traps to track adult activity, you can use degree-day models to estimate when they will begin laying eggs on the fruit, which can inform when you should spray to stop those very hungry caterpillars before they damage the fruit.

There are several kinds of monitoring traps for the codling moth, but the key differences are cost and use of a sticky panel versus a closed container to capture adult moths. What’s in common among these traps however, is the use of a pheromone lure, which draws male moths into the trap by mimicking the smell of a female moth. The pheromone lure is placed inside the trap, near or above the sticky panel or closed container, and male moths fly into the trap, thinking they will find a female. It’s amazing technology! If you’ve never used these traps before, here’s the key steps you need to know and follow to use them correctly:

1. Where can you buy your monitoring supplies? There are several online vendors, but Great Lakes IPM is my go-to shop. You can order a few pheromone lures, or get a discount if you are buying in bulk. For the codling moth, you can purchase ready-to-use monitoring kits that typically include a tent-style trap with sticky panel, or a bucket trap, which is reusable and may capture fewer non-target insects. Be sure to wear disposable gloves when you handle pheromone lures and don’t use different lures in the same insect trap (i.e., don’t place lures for different insects in the same trap, and if you’ve used a trap to monitor codling moth, only use it for codling moth moving forward in the future).
2. When and Where to place your monitoring traps? Place your monitoring traps shortly before bloom so you can detect the earliest flight of male moths. At the research orchard here, we typically place traps mid to late April and monitor through August. To get the best capture, codling moth traps should be hung in the top-third of the tree and towards the edge of the canopy. This allows easy access for moths to enter the trap and allows the wind to move through the trap and carry the smell of the pheromone lure throughout the area, so male moths can detect it! Place traps within blocks of apple trees, rather than hanging them on trees located on the edge. In a backyard setting, you may only need a single trap, while in orchards you will probably want two traps per block of trees, with traps spaced at least 25 feet apart. In blocks of 5 acres or less, two traps (spaced as described above) is typically sufficient to detect codling moth activity.
3. How often should you check your monitoring trap? Once you place pheromone traps for codling moth, you will get the most helpful information from them if you check them daily, until you begin to see sustained (regular) capture of moths in the trap. So for example, you may check the trap daily and record many zeros, but then capture 1 moth here, 3 moths there…up until you capture many more, like 10 or 15 “all of a sudden,” on the same day (numbers are an example here, based on monitoring two traps in our Lafayette, IN research orchard). At this point, you have established biofix, which is key for those who are using degree-day models to estimate codling moth activity. Now you can begin checking traps twice a week rather than daily. Don’t forget to place new pheromone lures in the trap according to the manufacturer’s instructions – many lures are good for 1 month or so.

Last, but not least: be sure that you have correctly identified the insect in the trap! There are many similar-looking moths out there, and other kinds of insects that may end up in the trap accidently. After all your efforts monitoring codling moth, you want to be sure you’ve got the right pest so you can be confident that the management strategy you’re applying is effective against it! You can send pictures or insect specimens to us at the Purdue Plant and Pest Diagnostic Laboratory for confirmation.

I hope this is a helpful overview for how, when, and where to monitor codling moth! If you have other questions, don’t hesitate to reach out to your local county extension office or me by email (long132@purdue.edu).