NEIGHBORHOOD GARDEN FOR OCTOBER 29, 2016

******************************************************

WHERE DO INSECTS OVERWINTER?

BY GEORGE EDGAR

          I was cleaning up the garden and hoping I would have better luck next year in controlling the insects and varmints that destroyed our Butternut squash and ornamental gourds when I remembered a series of article I wrote a few years back. So I went back in my computer and printed them out to see what I said about cleaning up the garden and refresh my mind on what I learned about how insects overwinter. One of them follows.

          Insects have a variety of methods for surviving the coldness of winter:

1.  MIGRATION-Like humans, insects also have their “Snowbirds” that head south for the winter and then return. The Monarch Butterfly, the Painted Lady Butterfly, the Gulf Fritillary, and the Giant Swallowtail are the foremost examples of this maneuver.      

          Other pests such as leafhoppers, black cutworm, fall armyworm, cucumber beetles, and milkweed bugs head south and they reinvade the next year, but in this case, it is different individuals that will return in the spring and early summer with the help of southern winds.

2.  INVASION-“Most insects stay here year around. They employ a variety of tactics for survival. One is simply to move in with humans. Insects such as multicolored Asian lady beetles (ladybugs), face flies,   cluster flies, elm leaf beetles, boxelder bugs, and clover mites overwinter as adults in wall voids, attics and other out-of-the-way places in homes and other structures.” (1) In nature, many will seek shelter in leaf litter, rotten logs, or dense forest undergrowth.

3.  ACTIVATION- “Honeybees have been studied during the winter and

are found to remain semi-active in hollow trees and hives through the generation of body heat.  The consumption of 30 pounds of stored honey during the winter months makes this possible.  Heat energy is produced by the oxidation of the honey, and circulated throughout the     hive by the wing-fanning of worker bees.” (2)

4.  HIBERNATION-“This is the strategy employed by most of our

northern species of insects to avoid winter. However, ‘hibernation’ is really a concept that describes mammal wintering. Insects that go dormant in winter enter a state called ‘diapause’. Their bodies respond to changes in daylength, temperature, food quality and other environment cues”.  (4)

          “With few exceptions, insects that go dormant for the winter fit into two classes: freeze-susceptible and freeze-tolerant. A freeze-susceptible insect avoids freezing altogether by depending heavily on antifreeze compounds, called cryoprotectants, to supercool body fluids and tissues above their freezing point.  Ethylene glycol, the same compound found in antifreeze for cars, is the most common cryoprotectant.”

          “Freeze-tolerant insects do not really freeze, at least not totally.  Just the fluid, which bathes their living cells, freezes.  This freezing process forces water out of the living cells thus lowering the freezing point even further. (Smaller amounts of water freeze at lower temperatures than larger amounts of water). Freeze-tolerant insects aren’t necessarily more cold tolerant than freeze-susceptible insects. Each class of insects just has it own unique survival strategy. Both types of insects also are affected by other conditions that affect their rate of winter survival: size, moisture, nutrition, temperature, stage of growth, species.” (3)

Copyright 2016

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)