Winter Effects on Insect Pests
Many pests are impacted by winter’s climate conditions. For the most part, fungus spores are highly resistant to winter conditions but are much more sensitive to tillage than certain weeds and insects.
Grubs for example, over winter as larvae and many are killed by a pathogen that infects their outer skin, which desiccates (dries out) the body. Some insects, which normally over winter in surface residue (leaves, corn stalks, etc.) or soil don't locate themselves deep enough in the soil to survive winter and can be killed by cold temperatures. This winter, being milder early on, may cause an increase in the amount of insects that over winter and may bring increased insect pressure next growing season. On the other hand, if the mild weather forced some insects to start growth and the weather turns sharply cold, many insects will perish. A lot depends on the temperatures in February, the particular insect and if snowfall occurs. Snow insulates the soil and lessens the mortality of insects.
For example, Flea Beetle populations will be elevated when February temperatures are mild. Insect hatches usually occur when the host (preferred food of the insect) is present. If the host is not present in sufficient quantity to support the insects when they hatch then the insects will die. This is why crop rotation is critical because by rotating the crop (corn, soybean) the insect life cycle is broken and the insect population plummets.
For example, the most effective root worm (severe insect pest in corn) control in corn is to rotate to soybeans to break the life cycle. Another effective method is to wait 12 days after killing a field infested with chickweed or any other spring weed to allow the insects time to perish before planting corn. This will help to avoid damage to the corn stand. Once the food source is eliminated, the root worms die.
Many species of insects like root worms and grubs lay eggs in late summer. Last summer, the drought certainly impacted the moisture in the soil where the eggs were deposited and may have caused a condition where the eggs desiccated and populations could be lower. At this point, it is difficult to tell whether insects are going to be a problem in the summer of 2011 due to the early mild winter.
One can bet that certain fields will be infested with insects for reasons other than weather; such as rotation and tillage system impacts. Entomologists are expecting large populations of brown marmorated stink bugs and soybean aphids. It is wise to begin planning now to manage these pests. Seed treatments, in combination with postemergence applications of pyrethroids, may prove useful in managing these pests next season.
By understanding the behavior and requirements of pests more effectively, pest management programs may be developed to lesson our reliance on pesticides and ensure adequate control of pests. If you have an unknown insect, disease or weed or just want more information about a particular pest please visit or call your local extension office.