- Author: Belinda J. Messenger-Sikes
What is that weird wormlike thing in your garden? A slug? An earthworm? It may be neither—it it might be a land planarian. Land planaria are also called terrestrial flatworms and hammerhead worms. They are often colorful, such as the blue garden flatworm (Caenoplana coerulea) or patterned with stripes, like the shovel-headed garden worm (Bipalium kewense).
Land planaria are generalist predators of earthworms, slugs, and other mollusks. They capture prey by wrapping their bodies around it and engulfing the prey with mucous. Planaria mouths are not at the end of their body like most animals, but on the underside near the middle of their body. Unlike slugs, land planaria do not have tentacles (such as eyestalks), which is a useful way to distinguish them. Like snails, they are hermaphroditic, meaning each individual has both male and female reproductive organs and can mate readily with any other worm of the same species. Land planaria can also reproduce by binary fission, which is when one individual planarian splits into two. You may remember an experiment from middle or high school science laboratory where a planarian cut in half regrows into two separate planaria.
These animals need moisture, so they live in wet environments. Examples include under rocks and logs, in plant pots and mulch, under bushes, and along streambanks. In nurseries, they are commonly found under plant pots. After heavy rains, they might be found on sidewalks and driveways.
Do land planaria cause problems?
Land planaria may be considered minor pests, but they don't damage plants or harm people. They can sometimes reduce earthworm populations in natural environments. Land planaria have very few predators since their mucus is distasteful. While some species (B. adventitium and B. kewense) produce a neurotoxin, they cannot inject it into pets or people and are only toxic to small animals when eaten. Some species can carry rat lungworm, an internal parasite. Wash your hands thoroughly after handing land planaria to avoid these problems.
Some land planaria are invasive, but their impacts on the environment and native flora and fauna will depend on the species, their prey preferences, and where they are introduced. In most cases, there is little impact. Invasive land planaria may present problems in the future since it is easy for land planaria to reproduce and spread.
Eradication of land planaria from a landscape is difficult, if not impossible. Cutting up planarians to kill them doesn't work since new individuals will grow from each section. They can be killed with salt or by submerging them in rubbing alcohol, but this is impractical for large numbers of planaria. There are no registered pesticides for land planaria and using a molluscicide to control them is ineffective and may be illegal, since land planaria are flatworms and not snails or slugs (mollusks).
[Originally featured in the Spring 2023 issue of UC IPM's Home & Garden Pest Newsletter]
- Author: Dr. Anthony Fulford
What is subsoil?
There are several layers (also known as “horizons” to soil scientists) that can be found when we dig deeper and deeper down into the soil. We can imagine all the individual layers of a soil stacked one on top of the other like a layer cake, this is called the soil profile. The surface soil is the uppermost layer of the soil profile, and the one we are most familiar with, because this is where most of the action takes place. Soil mixing with tillage, compost and fertilizer application, irrigation, plant root growth, and animal activity (including microbes) are mainly concentrated within the soil's surface layer. Additionally, decomposition of plant and leaf litter occurs most rapidly in the surface soil, this eventually leads to the formation of new soil organic matter. In comparison, the subsurface soil, or subsoil, is composed of one or more soil layers that lie below the influence of surface soil activities. There is not a consistent depth at which every surface soil layer changes into the subsoil layer(s), rather the subsoil occurs at a different depth from place to place depending on numerous factors, including some of the factors mentioned previously. This is the reason why it is difficult to determine where the subsoil layer begins in the soil profile.
What does subsoil contain?
What does subsoil look like?
What is subsoil used for?
In general, the subsoil is a less suitable medium for plant growth compared to surface soil because of some of the factors mentioned previously. There are properties of subsoil however that make it suitable for other uses such as a source of “fill soil” for “cut-and-fill” construction operations, as a source of clay for building materials, and as an absorption layer for on-site wastewater disposal.
What can home gardeners do to keep their subsoil in great shape year after year?
What is the substratum layer of soil? Does that layer affect gardening at all, and if so how?
What is the bedrock layer? Does that layer affect gardening at all, and if so how?
Bedrock is the bottom layer of the soil profile layer cake. The bedrock layer consists of solid rock that has not yet been exposed to the chemical, physical, and biological processes of the surface soil and subsoil. In some places, bedrock is the foundation from which the overlying soil layers developed, while in other places, the bedrock layer may have become “buried” by windblown sand or sediment. Bedrock does not directly influence plant growth, but it can determine the type of clay minerals found in different layers of the soil profile.
Dr. Anthony Fulford is the Area Nutrient Management and Soil Quality Advisor for Stanislaus, Merced, and San Joaquin Counties.
/h3>/h3>/h3>/h3>/h3>/h3>/h3>- Author: Ben Faber
Earthworms are commonly associated with “healthy” soils and in many cases they are good indicators. See a previous blog: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=23945
In a recent blog, Michigan State University is telling a different story: http://msue.anr.msu.edu/news/the_dirt_about_earthworms
The popular view of earthworms – beneficial creatures that aerate the soil, feed robins and make good fishing bait – may be true in our gardens and tilled farm fields, but in forests it is a different matter.
Earthworms are not native to Michigan and the Great Lakes region, at least not since before glaciers covered the region; they were brought here during European settlement in the 1800s or possibly earlier. Plants, wildlife and forests evolved without any of these creatures around. They are now an invasive species that harms forests.
In gardens and agricultural fields, earthworms help improved soil structure and fertility, but in forests their effects are much different. Hardwood forests without earthworms have a thick layer of slowly decomposing leaves, or “duff” that promotes a rich community of wildflowers, tree seedlings and small animals. Earthworms change that environment dramatically by essentially consuming the duff, thereby destroying habitat and reducing fertility. In contrast to their effect in gardens, earthworms cause forest soils to become more compacted. As a result of habitat loss, fertility declines and soil compaction, these forests may be less productive and have poorer new tree regeneration in the long run.
If that wasn't bad enough, research shows that the combination of excessive browsing by deer (another serious threat to Michigan forests) and high earthworm populations in an area can have a worse effect than either one alone. Also, other invasive species, such as buckthorn, may have an easier time getting established in earthworm-infested areas. Without a diverse forest floor and new seedlings, the long term health of woodlands is threatened.
The connection between climate change and earthworms is complex. A warmer climate and longer growing season may hasten earthworm migration to previously worm-free forests. Introduction of earthworms make them more vulnerable to other climate-related stresses, such as more frequent and longer droughts. Although earthworms may reduce the amount of carbon entering the atmosphere through their soil action, on balance these creatures are a bad deal for northern forests.
Earthworm populations are not the same throughout Michigan forests – some areas have dense populations, others have few or none. They get from place to place very slowly. People, however, can transport them much more quickly on muddy tires, soil moved from place to place, and discarded fishing bait. There is no way to eliminate earthworms once they become established in woodlands.
In California, we have some native species of earthworms, but in many cases, non-native introduced species have come to dominate. The predominant native species belong to the Argilophilus and Diplocardia while many of the non-native are of European in origin in the Lumbricidae family. Many of these non-natives were probably introduced by settlers bringing plants from home, which had soil containing the worms. A survey of California earthworms by the US Forest Service can be found at:
https://www.fs.fed.us/psw/publications/documents/psw_gtr142/psw_gtr142.pdf
This is a wonderful description of earthworm biology and their occurrence in the California landscape.
![earthworm earthworm](/blogs/blogcore/blogfiles/51031.jpg)
- Author: Ben Faber
Leafminer, sometimes Leaf Miner. It's that time of year. Those little moths come out in the late afternoon and flit about. They lay their eggs and when they hatch the larvae start burrowing through the leaf. The recent heat and also the generally warm summer have set them off. And it is obvious now. The heat has exacerbated the collapse and drying of the leaves and on older trees it looks like trees have been decorated with a sprinkling of light brownish ornaments. It is disturbing. But it's not the end of the world, like …………ACP can be.
Leafminer adults are tiny moths less than 0.12 in long (2 mm) with wings span twice as wide.
Pretty shocking from a distance
Citrus leafminer larvae feed by creating shallow tunnels, referred to as mines, in young leaves. It is most commonly found on citrus (oranges, mandarins, lemons, limes, grapefruit and other varieties) and closely related trees (kumquat and calamondin). The larvae mine the lower or upper surface of the leaves causing them to curl and look distorted. Mature citrus trees (more than 4 years old) generally tolerate leaf damage without any effect on tree growth or fruit yield. Citrus leafminer is likely to cause damage in nurseries and new plantings because the growth of young trees is retarded by leafminer infestations. However, even when infestations of citrus leafminer are heavy on young trees, trees are unlikely to die. But they can sure struggle pushing new leaves that then get attacked anew.
Several years ago, we did a trial where we sprayed mature trees with leafminers every month for 18 months with a rotation of different chemicals and even the most heavily treated trees had some damage on them. The most heavily infested trees looked horrible, but in that period of time there were no lemon yield differences. Young trees treated with a systemic were able to free themselves of infestation. This has been commented on by others, that soil applied systemics on heavier soils can have problems controlling leafminers.
http://ipm.ucanr.edu/PMG/r107303211.html
Photos: Tunnels and the rapidly dried leaf after a heat spell
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: Hello. The picture (right is from my garden with this “mysterious” worm crawling around on my vine. I can't tell from my internet search if this is an elm worm, rose worm or (very important) will this become a butterfly or a bad moth? Please help!! Thanks.
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk. I apologize for taking so long to answer, but this is a busy season.
From your excellent photo, the caterpillar looks like a gulf fritillary, which is a butterfly. These butterflies are large, about the size of a monarch. They are found primarily in the southern US and south through Mexico all the way to South America, and, strangely enough, into California where they were introduced sometime in the 1800s. They are often raised to be released at events such as weddings. The caterpillar feeds only on passion vines. Is that where you found yours?
![Gulf Fritallary butterfly Gulf Fritallary butterfly](http://ucanr.edu/blogs/CCMGBlog/blogfiles/45333.jpg)
Please let us know if you have further questions.
Client's Response: Thank you so much. Since they are good (butterflies not coddling moths), I am glad I didn't disturb them. And yes, they are on my passion flower vine. Thanks again.
Help Desk of the UC Master Gardener Program of Contra Costa (SEH)
Note: The UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. We can also be reached via telephone: (925)646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).
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