RICHMOND, Va. (WRIC) — As the weather gets warmer, you might be getting the urge to finally head outside and plant a beautiful spring garden, or make sure your lawn is lush and green. But some slithering creatures could derail your garden goals — worms.
While some worms like earthworms greatly benefit their environment, some invasive species of worms can harm plants — and even humans or animals.
In recent years, you may remember hearing about hammerhead worms or armyworms popping up in Virginia, both of which can cause problems for very different reasons. Here is your guide to what those pests are, how to identify them and what you can do if they wiggle into your garden.
What are hammerhead worms?
Hammerhead worms — also known as hammerhead slugs — tend to be found in hot, humid climates that are similar to their native southeast Asia. Because of this, they can be found in greenhouses and are most common in states like Alabama, California, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Texas, according to the Texas Invasive Species Institute (TISI).
The worm’s name comes from its half-moon shaped head, similar to a hammerhead shark. It is usually light colored with one to five dark stripes, and can be up to 15 inches long, although lengths of eight to 12 are more common, according to TISI.
What are armyworms?
The fall armyworm is a tropical caterpillar which turns into a moth later in life and is native to warm climates in the western hemisphere, according to Virginia Tech. They are not native to Virginia, but the commonwealth has seen large outbreaks in both 2018 and 2021. Female moths can lay up to 10 egg masses, each with around 100 to 200 eggs, which can cause massive outbreaks if enough moths fly into an area.
According to Texas A&M University, fall armyworm caterpillars can be brown, gray, green or yellow-green. Their distinguishing features include a white inverted Y between the eyes and three white stripes behind the head. Adult armyworm moths are typically gray with white underwings and their wingspan is one and a half inches long.
When do they appear?
Hammerheads are likely to come out of hiding when it is particularly warm or damp, like on a rainy day, according to North Carolina State University.
Fall armyworm moths often fly in and appear in the eastern United States during late summer and fall, although they have been known to appear earlier, according to Virginia Tech. The moths could be seen in central Virginia in mid summer during a 2021 outbreak. However, the moths cannot overwinter in Virginia, so populations will usually disappear when it gets cold. The life cycle of an armyworm is also complete in about 30 to 40 days, so the worms will not be larvae for long.
What do they do?
Hammerhead worms produces a neurotoxin they use to hunt earthworms and other prey. This neurotoxin can not only harm other types of worm that can fertilize the soil, but can also be harmful if humans touch them or pets eat them, Dr. Nathan P. Lord from Louisiana State University told WGMB Fox 44 last year. According to North Carolina State University, some flatworms can carry rat lungworms, a parasite that can infect people or some animals if the worm is eaten.
Armyworms are more harmful to your lawn and to grain crops than to people or pets. Large amounts of newly hatched worms can completely destroy grass in lawns and gardens, as well as sod plantings, hayfields, and alfalfa fields, according to Virginia Tech.
What can you do about them?
To protect yourself from hammerhead worms, the TISI suggests wearing a pair of gloves while gardening to avoid touching the worms. If you do touch one with your bare skin, wash your hands with hot, soapy water and rinse them in alcohol or use hand disinfectant.
Hammerhead worms can also be killed, but it takes a little extra effort. They can be squished, according to Lord, but one of the most effective ways to kill them is to put salt on them and wait for the worms to dry out in the warm sun.
However, be careful not to cut them up and break them into pieces. According to the TISI, hammerhead worms reproduce through a process called “fragmentation.” According to Lord, this means that through specialized cells, hammerhead worms can regenerate parts of their body. This means that a worm cut into pieces may just turn into an entirely new worm within a few weeks.
If you’re dealing with an armyworm problem, on the other hand, they are a bit easier to handle. According to Virginia Tech, insecticides are the most common way to control armyworms, although it can be difficult to control a large amount of larvae. On grass, pyrethroids such as Biomist, Scourge and Anvil insecticides seem to be most effective on armyworm larvae.