Insect activity has been a concern in South Dakota because of the warm winter we have had this year. And from that concern, questions have emerged:
- Why am I seeing so many insects in my house?
- What does this weather mean for winter survival of pest insects?
- What’s in store for us this year?
These are just a few of the questions that many of us have, and in reality, these are not questions that can be answered out right or even simply for that matter… But in an attempt to quench your lust for insect-related knowledge, I should probably start with a quick insect biology lesson!
As many of us know from years of DISTANT observation- insects are smaller than us… Sounds pretty basic, but hang with me here… Insects are smaller than humans, and because of this lack of magnitude, insects are incredibly dependent on external temperatures and environmental conditions. Insects are ectothermic meaning that they cannot internally regulate their body temperature. They instead rely on a mixture of direct sunlight and shade to achieve a balanced body temperature. Like many reptiles or amphibians, insects also rely on temperature to regulate their metabolism. This means that insects are much less aggressive feeders under low temperatures, but feeding and metabolism increases with temperature up to a certain degree.
Now that we have that cleared up, we can get back to the reason you’re reading this article… your questions!
Right now, many of us (myself included) are observing what could be mistaken as an insect “uprising” in our homes. This increase in activity is directly related to the warm weather we’ve been having. Many of those insects have been overwintering in your homes since the late fall and now that temperatures are appropriate for survival, they’re leaving… Like us, insects don’t particularly enjoy being confined within the walls of our homes or offices on nice sunny days and are just looking for an exit. Lots of residents have already flooded the Wal-Mart, Target, and other general stores for cans of insecticide. As an entomologist, I can only ask that you please put your cans down and give these buggers a little bit of time to find their way out of your home and into the great outdoors. For those brave souls out there, give them a hand (or tarsi) and place them outside.
From a producer’s stand point, this past “winter” is a big concern because that hope of reaching temperatures cold enough to decimate harboring pest populations is pretty well vanquished. Or is it? Many insects overwinter above ground in various crop fields or rangelands. These particular insects would prefer a mild winter to increase survivability, but if you recall back to early February, we had some pretty cold weather with little to no snow to act as an insulation layer for these particular insects which in turn could increase their mortality rate. However, insects that overwinter below the soil surface may have a higher survival rate because soil temperatures remained higher.
With all of those warm, winter days insects were more likely to become active before their regular food sources were available. Before overwintering, insects store up energy in the form of lipid reserves. If an insect were to become active and use up their energy reserve before food becomes available, they can die. The risk of death is also increased when activity starts before all of the cold weather is over. Early warm fronts can trick insects into leaving that dormant winter stage just before a cold front moves back in. This can be extremely hard on insect bodies if they are unable to find suitable cover from the cold.
So to give you a more direct answer regarding insect survival rates or future prospects for pest insect densities… There are way too many factors to say that they won’t be here or will. And therein lies the excitement of agriculture and nature as a whole. The realization that the picture is far too big to get a grip on and that it is up to us to monitor the things we can and make the most educated decisions when it comes to pest control in your home or in your field.
But rest assured, if a pest had an easy winter to survive, so did all the beneficial insects and pathogens.