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By Roberta Tolan
It’s official — winter is here and the early morning temperatures are regularly in the single digits. We humans respond to the cold by cranking up the heat in our homes, putting on warmer clothes and continuing on with our regular daily routines. Insects, on the other hand, often respond by undergoing major changes to survive. The following information on how insects respond to our cold Colorado winters was taken from an article written by Dr. Whitney Cranshaw, Colorado State University Entomologist, published in the CSU Extension Sustainable Small Acreage Newsletter, Fall 2013, Issue 19.
Some insect species die out over winters, such as those that annually recolonize the state with spring and summer migrations. Others prepare for winter in several different ways. Caterpillars and beetles tend to burrow into soil or other protective cover. Aphids produce cold-resistant eggs that are attached to buds and needles. Several species like the protection that buildings and homes provide, producing nuisance problems.
Regardless, most species that successfully overwinter undergo physiological changes as well. Insects become “cold-hardy” in the fall, which involves chemical changes, including the production of anti-freeze that protects their cells from lethal freezing. At this time, most insects are also in a condition known as diapause, a semi-dormant state where reproduction, development and most feeding ceases. Diapause persists for months and is only ended when certain environmental triggers are passed. Day length is sometimes used to determine when diapause occurs; a critical exposure to chilling temperatures may also be required to end diapause.
The following is a summary of how many arthropods in the state survive winter.
Most Colorado butterflies spend the winter as pupae in sheltered corners, often several yards from the plants that, when in the caterpillar state, it fed on. However, a few manage to tough it out as adult butterflies, notably the Mourning Cloak, which may even be seen flying during warm days in winter.
Several butterflies, including the Monarch, Painted Lady and Variegated Fritillary, show true migration into the state during spring, followed by a southern migration in late summer. The Monarch overwinters in the butterfly stage in a fairly restricted area in the highlands of Mexico.
Ants are social insects that maintain a colony from year to year. Underground nesting is the norm, although some nest in wood or around homes. Over-wintering stages are adults, both workers and fertile queens. With warmer temperatures in late winter, eggs are laid and new ants are produced.
Honey bees are social insects that also maintain a colony from year to year. Almost all honey bee colonies are in maintained hives, although a few wild colonies occur in hollow trees, hollows of walls and other protected sites. Overwintering stages are workers and a single queen. Egg laying is suspended in fall and begins again during late winter.
Yellowjackets, hornets and paper wasps
Yellowjackets and hornets are social insects that abandon the nest at the end of the season and start a new colony each spring. Overwintering stage is a fertilized queen, which hides in protected sites such as under bark, around buildings and other locations. In spring, surviving females attempt to individually establish a new colony, a project that is rarely successful. Colonies that do become established grow slowly during the early season, when the queen and a few worker wasps are available for colony chores. However, as the season progresses, colonies expand rapidly. At the very end of the season, queen and males are produced. By early fall, the colony is abandoned and the workers and males die.
Bumble bees are social insects that make a new colony each year. The only stage that overwinters are the large, fertilized queens that hide in protected areas. In spring, the queens emerge and try to establish a colony in abandoned rodent or bird nests or in hollows that have insulating material nearby. As the colony is originally produced solely by the efforts of the single queen, the first workers produced are malnourished and small in size. However, as these later workers are produced to help with colony chores, the colony becomes full-sized in late summer before it is abandoned.
Lady beetles overwinter in the adult stage, typically seeking protected locations in the general vicinity of where they spent the summer. In particularly good sites, they often will winter in clusters. One species that recently established in the state, the multicolored Asian lady beetle, frequently winters in homes.
A few of the lady beetles may migrate long distances seeking winter shelter, including at least two species which fly to the mountains and spend the winter under the snow at elevations typically above 9,000 feet. These beetles often occur in spectacular aggregations that are most commonly observed during fall. The beetles then fly to lower elevations in late spring as snow melts. Mass winter aggregations occur all along the Front Range, but apparently they do not occur in western Colorado.
Most aphids overwinter as eggs on some trees or shrubs. A typical Colorado aphid life cycle involves feeding on an herbaceous summer host plant followed by return of the aphid to a perennial plant in late summer and early fall. For example, the green peach aphid is a common garden pest in summer, but only survives winters on various Prunus species; potato aphid, another common garden pest in summer, survives as eggs on rose plants in the winter. Some aphids, notably the Russian wheat aphid, overwinter on the plant on which they feed, continuing to feed and develop throughout winter as long as temperatures permit. Other aphids, such as the cotton aphid and greenbug, rarely survive Colorado winters and most found during the summer originate as annual migrants from more southern areas.
Grasshoppers and crickets
There are a lot of different grasshoppers in Colorado (60-plus species), and the ways they make it through the winter also vary. However, most of the damaging grasshoppers (certain Melanoplus species) and crickets overwinter as eggs, in an egg pod inserted into soil. Other species overwinter as adults and even nymphs.
CPR and First Aid
CPR and First Aid Certification classes are now being offered monthly by the CSU Extension office on the second Monday and Wednesday of each month from 6-10 p.m. Anyone needing to receive or renew certification can register by calling the Extension office at 264-5931. We will also attempt to schedule classes on additional dates with five or more registrations. Cost for the classes is $80 for combined CPR/First Aid and $55 for CPR, First Aid or recertification. The type of first aid information provided will vary with the needs of the audience.
Back to basics food preservation
The CSU Extension Office in Archuleta County is offering a series of classes on basic food preservation.
Each class will cover basics of food spoilage, food borne illnesses, high-altitude adjustments and canning basics. Please contact the Archuleta County CSU Extension Office at 264-5931 or firstname.lastname@example.org to register. Space is limited so reservations will be on a first-come, first-served basis. Cost for the entire class series is $45 if paid in advance. Each individual class is $10 if paid in advance or $15 at the door. Each person will get to take home one jar filled with what was made and class handouts.
Jan. 13 and 27 — Jams and Jellies, 1 or 6 p.m.
Feb. 10 and 24 — Whole Fruit Canned, 1 or 6 p.m.
March 10 and 24 — Pickling/Freezing/Drying, 1 or 6 p.m.
April 14 and 28 — Tomatoes and Salsa-Canned, 1 or 6 p.m.
May 5 and 19 — Vegetables/Pressure Canning, 1 or 6 p.m.
Jan. 7 — Veterinary Science 4-H Project meeting, 4 p.m.
Jan. 7 — Colorado Kids 4-H Club meeting, 6:30 p.m.
Jan. 9 — Mountain View Homemakers noon.
Jan. 9 — Shady Pines 4-H Club meeting, 6:30 p.m.
Jan. 10 — Clover Buds 4-H Club meeting, 2 p.m.
Jan. 10 — Pagosa Peaks 4-H Club meeting, 2 p.m.
Colorado State University Extension is your local university community connection for research-based information about natural resource management; living well through raising kids, eating right and spending smart; gardening and commercial horticulture; the latest agricultural production technologies and community development. Extension 4-H and youth development programs reach more than 100,000 young people annually.
CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.