Many different nematodes exist as there are more than 250,000 species worldwide. Some eat plants, decayed organic material or live in, or on animals. Each species is usually specific in its habits. Of the parasitic nematodes, some invade the insect and consume it from the inside (endoparasitic). Other parasitic nematodes kill their hosts by infecting them with toxic bacteria, and then consume the soupy mess of bacteria and decay (entomopathogenic). This second group discussed here is of the phylum Nemotoda and the order Rhabdita. These entomopathogenic nematodes are too small, .6mm to .02 mm, to be seen without a field microscope or hand lens. These non-segmented roundworms (also called threadworms) hunt and destroy over 230 insect pests. When they sense the right soil temperatures, CO2 emissions and excretory products of soil borne insects, they attach and enter through body openings. Once the nematode releases their bacteria, the insect succumbs from the toxins and is dead within 48 hours. The Steinernema species carry Xenorhabdus bacteria. They live near the soil surface and enter into the insect through natural openings. Some, like the Steinernema carpocapsae, sit and wait for their hosts to come near. The targets they chose are army cutworms, billbugs, black turfgrass ataenius, crane flies and lawn moths. The Steinernema gaseri, on the other hand, is more mobile, hunting and targeting white grubs and borer larva. The Steinernema feltiae prays on dipteran pests like fungus gnats. The corpse of a Steinernema’s host is characteristically gray. The Heterorhabdis species carry Photorhabdus bacteria. They live deeper in the soil near the root zone and prefer moister soil. While also entering though the natural opening of the insect, Heterorhabdis can also pierce the insect exoskeleton. More mobile than the Steinernema, they hunt and infect root weevils, and white grubs, but also ants, fleas, moths and beetles. An insect infected by Heterorhabdis appears reddish-brown after it dies. The life cycle of these nematodes consists of six stages. After the egg, there are four juvenile larval stages, and then the adult stage. The third juvenile stage, called a dauer, is the infective predator. Dauers travel through the soil particles on a thin layer of water. After finding a host, the dauer injects the bacteria, whose toxin kills the host in a short time. Nematodes living in the host go through several generations before they consume the entire insect, leaving just a carcass. As the adults exhaust the food supply, they morph into dauers and the dauer larvae leave to find a new victim. Predatory nematodes have been studied for about 50 years as a safe and effective means to control insect pests. Commercial producers ship beneficial nematodes in their third juvenile stage in a medium that when dissolved in water, produces dauers in the millions. The product is sold under trade names such as BioSafe, BioVector, ScanMask, Exhibit, OtiNem and Guardian. The shipment can be stored in the refrigerator several months at 35 to 50 degrees, if necessary. Successful application depends on optimal soil conditions. Apply in the spring or fall when the temperatures are moderate and there is an abundance of soil insects. Contact your local Extension agent to find our when the larval stage of your target insect is present. These dauers are tolerant of pressure sprayers as well as other conventional spraying techniques. They will not survive in dry conditions, so irrigate the ground well before and after application. Added moisture may also encourage grubs to move higher up in the soil. Apply late on a humid day because ultraviolet light can kill the dauers. Sandy soil is easiest for the juveniles to move in, clay less so. A heavy thatch or mulch can hamper their progress. Colorado is home to hot, dry and cold conditions which can greatly reduce effective populations of beneficial nematodes. The persistence of nematode populations shipped from commercial producers in the humid South is questionable. However, if applied in optimal conditions, the dauers can effectively reduce insect pests in one season. Six reasons why these nematodes are beneficial:
Sources:
Garden Insects of North America, Second Edition. Whitney Cranshaw & David Shetlar Oregon State University Extension Service, “Control Sneaky Root Weevils with Beneficial Nematodes,” by Kim Pokorny University of California Agriculture and Natural Resources State-Wide IPM Program “The UC Guide to Healthy Lawns - Manage Pests With Beneficial Nematodes “ University of Connecticut Home and Garden Educational Center, Lady Bug Blog Fact Sheet “Beneficial Nematodes” CSU Extension Service Fact Sheet 5.573 “Insect Parasitic Nematodes” WS Cranshaw and R. Zimmerman Gardening Know How (website) “Nematodes as Pest Control: Learn About Beneficial Nematodes” by Amy Grant
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Colorado is home to endless outdoor activities, especially in the summer months. The state is also home to an abundance of flora and fauna, including native and non-native species of some stinging insects, which can sometimes get in the way of that outdoor fun. Most of the time, a select few of these nuisance species are responsible for most stings and unpleasant encounters. However, not every yellow stripey buzzing thing is a pest, and most bees and wasps mind their own business, and go about their day collecting food and resources (seldom noticed by anyone). In fact most of these insects (including those mentioned below) are considered to be beneficial organisms that play a role in providing valuable services: bees are well-known pollinators and most wasps are important predators and parasitoids of several other arthropods, which help keep pest populations at manageable levels. Here are two of the most common stinging wasps of Colorado:
Aside from the above wasps, there are a few other insects that are known to sting (though, usually only when disturbed/threatened).
It is important to consider the fact that: although many of these insects have the capability to sting- they provide important ecosystem services including pollination and pest control, without which our landscape would be very different from what we see today. Minimizing the proximity to their nests can play a role in reducing unpleasant interactions, and removing colonies from high-risk areas (including near playgrounds, schools, indoor structures, and patios) can sometimes be necessary. [This article has also been posted on the CO-HORTS Gardening Blog: http://csuhort.blogspot.com/2019/06/colorados-yellow-stripey-things.html ] To learn more about some of these nuisance wasps, and how to trap them, check out this Blog Post: http://csuhort.blogspot.com/2019/04/springs-not-so-nice-things.html For more information summarizing these stinging insects, check out these resources: https://webdoc.agsci.colostate.edu/ipm/COStingingInsectsFINALgb.pdf https://extension.colostate.edu/topic-areas/insects/nuisance-wasps-and-bees-5-525/ https://extension.colostate.edu/topic-areas/insects/european-paper-wasp-5-611/ Coming out of a challenging growing season filled with record high temperatures and severe to extreme drought designations through most of Colorado- we need to work towards tending to our drought-stressed landscapes, in order to set ourselves up for a successful 2019 season. Most trees have shallow roots, found in the first 18 inches of the soil. These sub-surface roots are vulnerable to dry conditions, and require supplemental watering in particularly hot and dry seasons. A drought-affected landscape has depleted its subsurface soil moisture content, requiring extra care in the fall to restore soil moisture for plants. This fall and winter care is critical in restoring that soil moisture that plants will rely on, going into the following growing season. Supplemental watering in the fall and winter are an important aspect of caring for a Colorado landscape in drought-affected areas. A combination of dry conditions, higher elevation, wind, increased sun intensity, and limited moisture make winter watering a critical component of Colorado gardening. CSU Extension recommends watering within the drip-line (the soil area from the trunk to the outer edges of the branches, similar to the ‘footprint’ of a tree or shrub) to a depth of around 12 inches once or twice a month from October through March. You can use several different methods to water, including soaker hoses, soil needles, and spray nozzles/wands. Younger trees and new plantings require more watering than established landscape trees and shrubs. Watering should take place in dry winters with no snow cover. It is important to only water your landscape plants when daytime temperatures are above 40 F. Restrict watering to mid-morning, allowing time for the water to percolate to the roots, before the possibility of an overnight freeze.
Apply 2-4 Inches of mulch (leaving 6 inches from the base of the trunk). Mulching provides insulation, and helps to conserve moisture in the soil. For more Information: http://extension.colostate.edu/docs/pubs/garden/07211.pdf http://planttalk.colostate.edu/topics/trees-shrubs-vines/1751-fall-winter-watering-drought/ http://csuhort.blogspot.com/2018/11/normal-0-false-false-false-en-us-x-none.html Managing European Paper Wasps starts in the Fall/Winter: with eliminating nesting spots to prevent Spring nest establishment. Don’t worry about taking down hard-to-reach European Paper Wasp nests from this past growing season- they will not re-use them. At the end of the fall, when temperatures begin to drop: workers will die off, and the queen will seek shelter in the ground to overwinter, moving out to seek an ideal nest location when temperatures start warming up again in the Spring. European Paper Wasps are a non-native wasp species that has become widespread in the state of Colorado. With records dating back to 2000/2001 in the Front Range, and possibly a few years earlier in the Western Slope: these stinging insects are becoming a nuisance in urbanized areas across the state. Similar to Yellowjackets (their stalkier cousins), these stinging insects can become aggressive in close proximity to human activity, and their social nature and aggressive behavior lends to their status as one of the most common unpleasant stinging interactions in the State of Colorado. Like many other paper wasps and hornets, European Paper Wasps will not re-use their nests from previous years, as they make a new nest each year- starting from scratch. Their nests are composed of a paper-like material fashioned into hexagonal cells. This is created from chewed up bark and other wooden materials. The best way to minimize populations around your homes is to remove ideal nesting habitat. These wasps like to nest in enclosed/sheltered areas, and can make use of spaces in grills, mailboxes, door jams of cars, and many more. Limiting access to these ideal shelters will reduce the likelihood of unpleasant interactions with humans. For areas that are far out of reach and out of the way, or unlikely to be encountered in the summer months- you do not need to worry about wasp prevention. European Paper Wasps have become one of the most important predators of many different yard and garden insects, and are considered beneficial.
In the summer months, established nests can be targeted with appropriately labeled pesticides. It is recommended that you wait until the darker hours of the late evening to spray these nests (after you have scouted and pinpointed their locations during the day). Again, this chemical control is only necessary in areas where nests will come in close proximity to humans, and may result in unpleasant interactions. Check out CSU Extension's Fact Sheet to learn more about the European Paper Wasp, their biology, and management: http://extension.colostate.edu/docs/pubs/insect/05611.pdf What are these NEW tiny insects that seem to be taking over my house? The simple answer: Elm Seed Bugs.
The long answer: Elm Seed Bugs, a newer pest to the State of Colorado (currently found only in the Western Slope), are likely something that you have seen this year. In most cases, you will notice these insects when they congregate on South or West-facing sides of your house, and when they sneak in to your home- you are even more likely to notice them. Sharing similar behaviors to their relatives, the Boxelder Bugs and the Western Conifer Seed Bugs, these insects are looking for shelter from adverse weather conditions (such as extreme temperatures, and seasonal changes, etc.). The primary reason for these seasonal ‘invasions’ is due to these insects’ overwintering behavior- leading them to warm, stable, indoor environments to survive through winter, followed by their move outside the home in the spring, where they reproduce to start the cycle again. Do I need to worry about them? No. Although these are newer insects to the state (with the first records beginning in summer 2017 in the Tri River Area), these insects do not cause any crop damage, structural damage, nor do they reproduce inside your homes. Their primary food source, like their name suggests, are Elm Seeds from Siberian Elm Trees (which are abundant in Colorado). How can I get rid of them? The best way to manage these nuisance pests is to prevent them from entering your home. Doing your best to seal any cracks and crevices, replacing damaged door sweeps and screens, and replacing any missing siding and paneling will minimize any of these invaders seeking shelter in your home. You can also use pyrethroid insecticides (labeled for outdoor structural use) outside window and door entryways as an additional barrier. If they find their way in, the simplest strategy to removing them is by sweeping or vacuuming them up and disposing of them outside or flushing them down the toilet. For more information about the Elm Seed Bug: http://extension.colostate.edu/docs/pubs/insect/05619.pdf Did you know that 99% of all insects are either harmless or benefit us in some way? Beneficial insects fall into 3 main categories:
Pests only comprise 1% of insects, so it is always a good idea to identify the critter you are looking at, before you decide to get rid of it!
Insect Identification services available at your Garfield County Extension Office! Stop by Monday through Friday between 8:30 am and 4:30 pm to drop off any insect samples for identification, OR make an appointment with your Agriculture / Horticulture & Natural Resources Extension Agent (Abi Saeed) for an in-person insect ID experience! Abi Saeed (970) 625-3969 [email protected] |
About the Author:Abi Saeed is an Entomologist with a specialization in Pollinators, Horticulture, Integrated Pest Management (IPM), Pesticides, Insect Identification, and Plant Pathology. |