NEIGHBORHOOD GARDEN FOR FEBRUARY 18, 2012

NEIGHBORHOOD GARDEN FOR FEBRUARY 18, 2015

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WHERE DO INSECTS OVERWINTER? PART #2

BY GEORGE EDGAR

The first part of February we had record high temperatures and I was cleaning the part of my garden I did not have done. Then the weekend of February 10 and 11 Lincoln had its first major snow (11.1 inches). And I thought about the many insects and mites I had seen in the summer and wondered, “Where are all the spider mites, grasshoppers, lady bugs, praying mantis, squash vine borers, and cucumber and squash bugs? How do they spend the winter? How do they keep from freezing? How do they get away from the snow?” While waiting for the snow plow to open up my street so I could get out on Sunday morning, I remembered these articles that I ran a couple years ago and decided it would be good to run again.

Jim Kalisch, in the Department of Entomology at the University of Nebraska-Lincoln helped me as I started my research on the original articles by recommending websites that I could research to find the answers. Many are listed at the end of this article.

Last week in part #1 I outlined that insects survive the coldness of winter by: A. Migration, B. Invasion, C. Activation, or D. Hibernation. Whether they (a) migrate, (b) invade our homes, garages and sheds, (c) hibernate, or (d) are active, winter is a period of dormancy for most insects. Especially the ones that stay in our hardiness zone #5. They seek protected places where they are not exposed to predators or repeated freezing and thawing. They survive in the least vulnerable life stage. The Insects (and do not forget mites) that will overwinter as:

· ADULTS: This includes boxelder bugs, lady bugs, cluster flies, most of the beetles, some aphids, most leafhoppers, and leaf beetles that hibernate in our eaves, homes, attics, barns, and sheds. Others invade hollow logs and other natural cavities.

· LARVAE: “Many insects successfully pass the winter as immature larvae.”(2) This includes the June beetles that survive as grubs that go deeper underground below the frost to survive for the winter. Other insect larvae protect themselves with a heavy cover of leaf litter or similar shelter. This includes the woolly bear caterpillar. And still other insects replace the water in their bodies with glycerol, a type of antifreeze, and find refuge away from wind and cold. Still others are the blackflies, and mosquitoes who are aquatic in the larval stage and spend their winter under the ice of ponds, lakes and streams going about their normal business but in a slightly more relaxed, cold-induced slow pace.

· NYMPHS: “Not many insects are active in the winter, but the nymphs of dragonflies, mayflies, and stoneflies live in waters of ponds and streams, often beneath ice. They feed actively and grow all winter to emerge as adults in early spring.” (2)

· EGGS: Fewer numbers of insects lay eggs which survive the winter. The most prominent insects in this category are grasshoppers, praying mantids, bag worms, tent caterpillars, the destructive corn rootworms, Gypsy moth, and most aphids that overwinter on trees and shrubs.

· PUPAE: Some insects overwinter in the pupal stage (cocoon), then emerge as adults in the spring. Moths in the Silkworm Family (Saturniidae) may be found attached to food plant branches as pupae in the winter.” (2) The cecropia moth, black swallowtail butterfly and tomato hornworm are also examples.

What about next year? “For some insects, if their overwintering sites get too cold (e.g. if there is little snow cover and very cold temperatures), they may have higher mortality, but won’t be eradicated by the cold by any means. They usually catch up in numbers later in the summer anyway.” (4) In general, insects are able to survive cold temperatures easiest when the temperatures are stable, that is not fluctuating through alternate thaws and freezes. But in the end, let’s put it this way: Have you ever known a summer without mosquitoes, or grasshoppers, or squash bugs?

So what can we do? “Many insects that attack your fruits and vegetables spend their winters nestled in the soil, under plant debris or protected by rocks, logs, lumber and other items found in or around your garden.”

“Cleaning up all plant debris and removing it completely from the garden is important in reducing favorable overwintering sites. Piling old vines, plants and trimmings in or near the garden and planning on getting rid of it in the spring simply provides insects with a place to survive the winter. Removing garbage cans full or empty, piles of tomato cages and stakes, hoses, and anything that can provide protection through the winter needs to be stored away from the garden” (5)

Like your mother always told you, “Put your toys away, and clean up your mess before you come in the house”.

References:

(1) “Where Do Bugs Go In Winter” by Don Janssen, Extension Educator for Lancaster County Extension Service. (lancaster.unl.edu/hort/Articles/2002/Winterbugs.shtml)

(2) “Where do Insects Go In the Winter?” Prepared by the Department of Systematic Biology, Entomology Section, National Museum of Natural History, in cooperation with the Smithsonian Institution. (www.edu/Encyclopedia_SI/nmnh/buginfo/winter.htm)

(3) “Winter Survival Strategies of Insects” by Bonnie Ennis, Colorado State University Cooperative Extension agent, horticulture. (www.colostate.edu/Dept/CoopExt/4DMG/Pests/winter.htm)

(4) “Where Do All The Insects Go In The Winter?” by Neil Carter, Tender Fruit & Grape IPM Specialist, Ontario Ministry of Agriculture, Food, & Rural Affairs and Hannah Fraser, Entomology Program Lead (Hort)/OMAFRA (www.omafra.gov.on.ca/english/crops/hort/news/

hortmatt/2006/01hrt06a5.htm)

(5) “Eliminate Insects Overwintering Sites” by Vaughn Hammond UNL Extension Educator at Kimmel Orchard in Nebraska City, Acreage E- news for October 2010. (http://environment.unl.edu/web/acreage/October-2010)