You’ve finally stored your grain, and it’s time to relax, right? Not so fast. Don’t allow all of the hard work you’ve put in this season go to waste because of a common pest. Indianmeal moths are just about everywhere and they can be difficult to deal with. We’ve uncovered some of best advice out there for recognizing and preventing Indianmeal moth infestations, as well as how to successfully manage their populations once present.
Signs of Infestation
DTN entomologist Scott Williams provides tips on how to identify Indianmeal moths and effectively manage them. The first sign of a problem is moths flying around in the top of grain bins. If you’re seeing them, it’s likely the population is fairly established. They’re about 1/2 inch long and mostly cream colored- but they can also appear a red-brown or dusty gray.
Indianmeal moths lay their eggs on their food source. They’re tiny and difficult to see. Once the eggs hatch, the larvae are easier to find. They can be cream, pink or even green colored bodies and darker heads. The larvae crawl around the grain and eat, all the while leaving behind trails of silk, fecal pellets and molted skins.
Elaborate silk trails can cause stored grain to clump together and harden. When fully grown, to about a 1/2 inch in length, the larvae will pupate. They’ll make their pupas in tight spaces, usually on the walls of the grain bin. Their brown pupas are 1/4 inch in long and covered in silk.
Indianmeal moth infestations can cause several problems with stored grain. Not only does their silk cause the grain to clump together, but they also leave behind their waste, which contaminates the grain. They consume your grain that’s meant for humans or other animals. Particularly bad infestations can lead to huge silk masses that may damage equipment. The masses are also dangerous for humans that need to enter the grain bins. They can collapse or fall down on top of workers. That’s why it’s necessary to use the proper safety equipment whenever entering a grain bin.
Prevention, Prevention, Prevention
To keep Indianmeal moths at bay, prevention is the best strategy. Before loading a grain bin, it needs to be cleaned properly. Once it’s cleaned of all grain, apply an insecticide like Tempo 20 WP or Tempo SC Ultra to the inner and outer walls of the bin.
When loading the grain, apply Diacon-D IGR (S-methoprene) or Actellic 5E (pirimiphos-methyl). These treatments are grain-specific, so make sure that you’re applying the correct one.
Keep the bin sealed and below 60 degrees. If you wish, you can hang pheromone traps 10 feet above the top of the grain to help monitor for infestations.
Entomologists Glenn Studebaker, Gus Lorenz, Nick Bateman, Neelendra Joshi and Aaron Cato of the University of Arkansas Extension provided some additional tips for keeping Indianmeal moth infestations at bay and managing them once they occur. In an article titled, “Preventing Stored Grain Insects in On-Farm Storage Facilities,” cleaning and treating to prevent infestation is emphasized.
Always start with a clean bin. Even a tiny amount of dust or leftover grain can result in an infestation of pests. Floors inside grain bins should be swept clean and any grain on the outside should be removed. An often overlooked area in grain bins are the augers. Once the bins are clean, treat with a residual insecticide like Storcide II, Malathion, Centynal or Suspend.
If planning on storing the grain for awhile, it should also be treated with insecticide. Consult the Stored Grain Insect Control section of MP 144 for a list of recommended insecticides and rates for stored grains.
If you see signs of infestation, the most effective treatment is to dispose of the grain and clean out the bin. Another option is fumigation. Phosphine gas or ozone are commonly used, and it’s advised to have trained professionals apply them. Fumigation treatments are extremely toxic, and can take anywhere from 3 to 5 days to be effective.
D.W. Johnson and L.H. Townsend, Extension Entomologists at the University of Kentucky College of Agriculture provide some tips on handling infestations. Once you hit this point you have two options. You can either move the grain and apply a protectant when you transfer it, or fumigate. Often it’s not possible to move your grain- especially this year with storage being tight. Fumigating, on the other hand is fairly inexpensive and effective.
Follow these tips in order to fumigate succesfully:
- Grain should always be level in the bin to let the fumigant penetrate evenly.
- Any surface caking or crusting should be broken up and removed.
- Grain temperature should be 60°F or higher to ensure proper vaporization.
- Possible leak points such as cracks or holes in the bin should be closed before fumigation since leakage may result in under treatment and poor control.
Fumigation can fail when not enough treatment is applied, leaky storage bins, excessive moisture above 12%, or when temperatures are too low or too high.
Hopefully, you’ve taken all the necessary steps to prevent from having to fumigate. Before storing grain, always clean bins and equipment thoroughly. Treat areas in and around the bin with insecticide, and treat your grain. Indianmeal moths can wreak havoc on your grain- consuming it, and leaving behind trails of silk and waste. With a lot of grain going into storage this season- especially soybeans- make sure you’re doing everything that you can to protect your bottom line.