The past few weeks have been “fun” with pest challenges in our garden and home. In the kitchen we battled ant infestations and pantry moths. In the yard the milkweed plants have been covered with oleander aphids, the California lilac (Ceanothus) was attacked by mealybugs accompanied by ants, and paper wasps (Polistes) have been trying to build a nest on the front porch.
How to tackle each of these issues? UC IPM (University of California Integrated Pest Management) Pest Notes and Quick Tips is my go-to for all these issues.
Inside the House:
Pantry Moths
Ants
In the garden:
Milkweed and oleander aphids (Aphis nerii)
I hoped I had escaped getting the detested orange oleander aphids this year, since in recent years they usually showed up earlier in the summer, but ultimately, they appeared. Most established plants can tolerate some aphids, but all aphids produce honeydew, which can attract ants and sooty mold. Since milkweed is the sole food source for the Monarch butterfly caterpillar, pesticides are not recommended. Thus, using strong sprays of water every couple of days helps manage them. Based on previous experience, I know they will reach the end of their life and ultimately disappear. https://ipm.ucanr.edu/QT/aphidscard.html
Mealybugs (Pseudococcidae)
Paper wasps (Polistes gallicus)
Thanks to UC IPM, which provides information on garden issues and pests, along with giving scientifically researched options on how to deal with them, I have managed to either control or eliminate these pesky pests.
UC IPM Resources:
The above links are to Quick Tips, short, to-the-point cards on each topic. They are available for free at local UC Cooperative Extension offices. The references below are for Pest Notes, which may have multiple pages and offer more detailed information about each topic.
Ants: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7411.html
Pantry Pests: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7452.html
Aphids: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html; https://ipm.ucanr.edu/PMG/PESTNOTES/pn7410.html
Mealybugs: https://ipm.ucanr.edu/PMG/PESTNOTES/pn74174.html
Wasps: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7450.html
Denise Godbout-Avant has been a UC Cooperative Extension Master Gardener with Stanislaus County since 2020.
/h3>/h4>/h4>/h4>/h3>/h4>/h4>/h3>- Author: Lauren Fordyce
You may not think about rodents such as rats, mice, or gophers until they become a pest around your home. Because rodents can be major pests in and around homes, gardens, landscapes, restaurants, and other buildings, each year pest control experts “celebrate” Rodent Awareness Week. Rodent Awareness Week (October 16-22) is an annual campaign created by the National Pest Management Association to educate the public about the potential harm associated with rats and mice. In addition to damaging structures and property, rodents can transmit diseases to humans and other animals. During the fall and winter months, rodents will seek food and shelter in homes and other buildings
Some general tips for keeping rodent pests out, include:
- Seal structural cracks and openings larger than 1/4 inch. Utilize weather stripping or door sweeps, and ensure doors and windows fit tightly. Wire screen can also be used.
- Keep food storage and garbage containers sealed.
- Remove or thin vegetation around structures. Rodents, especially house mice, will use climbing vegetation to scale buildings.
- Don't touch rodents with your bare hands. Dispose of dead rodents by placing them in plastic bags and putting them in the garbage.
- Avoid poison baits as the rodents can die in hidden places and they can be harmful to children and wildlife.
House Mice
Adult house mice can be 5 to 7 inches long with 3- to 4-inch-long tails. They are light brown to gray rodents with a characteristic musky odor. House mice are well adapted to living in close contact with humans. They are most active at night, but you can also see them during the day. Check behind boxes, in drawers, or around woodpiles for nests made of finely shredded materials. Control them by placing snap traps or glue boards in secluded areas along walls, behind objects, and in dark corners. Read the Pest Notes: House Mouse for more information.
Rats
The most troublesome rats are two introduced species, the roof rat and the Norway rat. Knowing which species is present is key in effective management. Norway rats arelarger than roof rats but usually have smaller ears and tails. When Norway rats invade buildings, they can commonly be found in the basement or ground level. They create burrows, holes in the ground, along buildings and beneath wood or garbage piles. Roof rats are excellent climbers so they can commonly be found in attics, walls, ceilings, and other elevated surfaces. They nest above ground in trees, shrubs, or dense vegetation. To learn more about rats, see the Pest Notes: Rats.
Of course, rats and mice aren't the only rodents you might find around your home and landscape. You may also encounter other rodent pests such as Voles (Meadow Mice),Deer Mouse, Gophers, Ground Squirrels, or Tree Squirrels.
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- Author: Carolyn Whitesell
- Author: Niamh Quinn
- Posted by: Elaine Lander
Regardless of what type of management option you use, you must first consider whether there are endangered or threatened species present on the property that may use ground squirrel burrows (such as burrowing owls, tiger salamanders, etc.). To check if there are endangered species on your property and to learn about proper uses of pest management products when these species are present, you can consult the PRESCRIBE tool. Trapping may still be an option if there are endangered species present, as long as you use and properly set specific trap designs, ensuring that they are inaccessible to endangered species. After determining whether endangered or threatened species need to be considered, you need to think through the pros and cons of each method, as explained below.
Toxic Baits
There are two categories of toxic baits available for California ground squirrel control: first generation anticoagulant rodenticides (FGARs, which require multiple feedings) and zinc phosphide (an acute toxin that may only require a single feeding). Many toxic baits are restricted use pesticides. Anyone applying a restricted material must hold a pesticide applicator's license and will need a restricted use material permit. A notice of intent must be given to your county ag commissioner's department at least 24 hours before the application of a restricted use material. Applicators then have up to four days after the planned date (the date on the notice of intent) to begin the application; otherwise, a new notice of intent must be filed. A written recommendation from a Pest Control Advisor may also be required. If you have any questions about what permits or paperwork are required for using a particular rodenticide, check with your local Agricultural Commissioner's office.
In general, when applying any type of rodenticide, always read the label carefully. The label will specify how to apply the bait correctly, the timing of subsequent applications (if applicable), the target species for which the toxic bait can be used, and the locations permitted for use. You must always have a copy of the label with you on site when you apply rodenticides.
FGARs can be used as spot treatments, broadcast applications (though not for resident use), or in bait stations. There is an antidote (Vitamin K1) available for the active ingredients in FGARs, but, since it is not 100% effective and requires a prescription from a veterinarian, these products should not be applied if you have any concerns that nontarget animals will be able to access the bait. There is a primary risk of nontarget exposure from the use of FGARs, however it is generally necessary for it to be consumed over multiple days, on multiple occasions to achieve a toxic dose.
Zinc phosphide does not have an antidote available and can only be used as a spot treatment or a broadcast application (NO bait stations). It is not permitted for use in or around buildings, and the label is species-specific for many locations, so always double check the label before applying it. You must be a licensed pesticide applicator to use this toxic bait to manage California ground squirrels. It poses a higher primary toxicity risk (due to direct consumption) but a lower secondary toxicity risk (due to consumption of a poisoned animal) to nontarget animals than the FGARs.
When using toxic baits, you should check for and properly dispose of squirrel carcasses daily. Always wear gloves when handling carcasses.
Trapping
For multi-catch live traps, which allow you to catch multiple ground squirrels at once, it is very important to pre-bait. That means you should place bait within the trap for a few days without setting the trap and allow the ground squirrels to feed on the bait freely. Pre-baiting will get the older and potentially trap-shy ground squirrels more comfortable with the trap and will increase your odds of catching them once the traps are set. When doing any sort of trapping, you are ideally looking to catch the adults, not just the younger, typically less wary, individuals. If you are able to catch a mature individual, its alarm calls will act as a form of bait in and of itself and will attract other ground squirrels into the trap.
To avoid contacting squirrel urine or feces, wear gloves when handling any type of trap, even if the trap is empty. You are required by the California Department of Fish and Wildlife to check the traps at least once daily.
Traps must be set more than 150 yards from any structure used as a permanent or temporary residence, unless such traps are set by a person controlling such property or by a person who has and is carrying written consent of the landowner to place the trap or traps.
California ground squirrels, once trapped, must be immediately killed or released in the site where trapped. Unless released, trapped animals shall be euthanized following AMVA guidelines or by shooting where local ordinances, landowners, and safety permit.
For more detailed information on ground squirrel control and other control methods not mentioned here, check out ANR's online resources Pest Notes: Ground Squirrel and the Ground Squirrel BMPs website.
[Article originally published in the Summer 2021 issue of the Green Bulletin.]
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- Author: Elaine Lander
Integrated Pest Management for Rats
- Our Pest Notes: Rats has information to help you with identification, biology and IPM options.
- This blog post provides additional information on using snap traps to catch rats and mice.
- If you are managing a school or community garden, you can find rat management information in this blog post.
Our UC Guide Page on Tomatoes also provides cultural tips and information on managing tomato pests if you have invertebrate pests or tomato diseases.
Wishing you a bountiful harvest!
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- Author: Niamh Quinn
- Posted by: Elaine Lander
Trapping is the safest and most effective method for controlling rats and mice in and around homes, garages, and other structures. Rodents that live in close association with humans are called commensal rodents. Rats and mice are the most frequently encountered commensal rodents in California.
Selecting the correct trap
Before trapping, make sure you know what rodent pest you have. It is a very common mistake to select the wrong size trap when you have not yet determined whether you have mice or rats (and the correctly identified rat species).
You will not catch a rat with a mouse trap, and you will not catch a mouse with a rat trap. To determine the difference between signs left behind by rats and mice, see our Pest Notes Rats and Pest Notes House Mouse.
Select traps that you can easily set. Older designs of rat and mouse traps can be difficult to operate, so if you are having trouble setting these traps, consider buying a newer design.
Choose the right attractant
Food attractant is a very important part of successful snap trapping. Select an attractant the rodent would likely find locally available or that you know they are already feeding on. The amount to use is also critical. Select a pea-sized amount of the food attractant and carefully place it on the trigger or in the trap recess before you set the trap.
Food is not the only thing that can be used to lure rodents to your snap traps. When trapping mice, you can try to use small bits of cotton or dental floss, as the mice will try and collect these for nesting material.
Be cautious about using peanut butter in areas where you are unsure who will access the traps. Many people have peanut allergies.
When using snap traps for rats, it is good practice to prebait your traps. This involves putting the traps with a food attractant in areas where you find rat evidence while leaving them unset for a couple of days until this attractant has been removed multiple times. Because rats are neophobic (afraid of new things), you want to make sure the adults as well as the juveniles become comfortable with the traps. Failure to prebait may result in the capture of juveniles only. The breeding adults are the most important targets.
Use multiple traps in the right places
Good trap placement is essential. Set traps along a wall or fence line or another linear surface like the edge of a planter to maximize the success of trapping. Be sure to trap with the triggers either facing the linear surface or with the traps along the side of the wall with the triggers facing away from each other. Rats and mice are smart and resourceful animals, so set your traps in ways that take advantage of their biology. While many rats and mice will choose to run along linear surfaces, not all will. It is important to consider this if you are having problems with catching the last few remaining rodents.
Be mindful of nontarget wildlife
Rats and mice might not be the only wildlife roaming around the yard, so be aware of other animals (nontargets) that might get caught in traps. Nontarget wildlife, such as birds, and even larger wildlife, such as raccoons, can fall victim to rodent snap traps. Set traps only during the night, but leave them where they are during the day, making sure they are not set. This greatly reduces trapping animals that are mostly active during daylight hours. To exclude other larger wildlife, try placing traps under a secured (weighted or staked down) milk crate.
Securing the traps by staking or tying can help somewhat with nontarget issues too. One other benefit of securing your traps is that they will be easy to find when they are triggered. Predators can carry away dead carcasses and often will take traps too if rodents are attached, making it difficult to find traps and use them again.
Safely dispose dead rodents
Successful trapping involves disposing of the carcasses. Always wear gloves when removing rodents from traps or even when working with traps that have come into contact with rodents, dead or alive. Rodents are vectors of many diseases, so even when just moving dead rodents, it is important to protect yourself.
If you catch a rodent, remove the rodent from the trap, double bag it and put it in the trash. Many municipalities do not allow for the disposal of carcasses in municipal waste so be sure to consult your local ordinances before disposal.
If you don't want to remove the rodent from the trap you can throw both the rodent and the trap away. There are also traps available that catch mice inside the trap and kill them; you then dispose of the whole trap. These types of traps are not available for rats.
Don't give up!
You must persevere with your rodent problem when trapping. It can take a long time to effectively manage a rodent issue in your home or yard. Be persistent. An ongoing trapping program might be necessary in order to keep the rodent problem at the desired threshold. Rats and mice are prolific breeders, so as you trap these rodents out, more may eventually come and take advantage of the resources in your area.
Be sure to check out the Pest Notes Rats and Pest Notes House Mouse for tips and information on sanitation, exclusion, and other methods that may help you successfully manage your rodent issues.
[Original article published as Snap Traps for Rats and Mice in the Winter 2019 issue of the Retail Newsletter.]
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