What's That Bug? does not endorse extermination

Subject: need help with ID of worm masses
Location: North Carolina
July 7, 2012 3:43 pm
Hi,
Can you help ID this mass of Asheville, North Carolina worms sent to me to ID (no luck)? Several masses of worms were found on concrete on their property.
Signature: John

Fungus Gnat Larvae

Dear John,
This is an aggregation of Fungus Gnat Larvae.
  Here is some information from the University of Delaware Cooperative Education website:  “As a result of our unusually wet weather, I’ve been receiving some interesting inquiries and digital images from arborists, landscapers, and homeowners. Their questions or observations are usually described to me as if they’re seeing ‘worms’, ‘tapeworms’, ‘processionary caterpillars’, or ‘armyworms’ crawling across the landscape, sidewalk or driveway. The masses are slimy or wet looking and several inches to several feet long as they move over landscape timbers and other surfaces. Even though this behavior is not yet understood entomologically, past experiences have allowed me to accurately identify these masses of larvae as an aggregation of darkwinged fungus gnat larvae. Observations of these masses of larvae are usually associated with a rich organic soil environment such as a recently mulched area where turfgrass is being established or shady, damp regions of the landscape. The larval stage of a darkwinged fungus gnat is thin, white, and legless with a shiny black head capsule. They have a smooth, somewhat transparent exoskeleton that reveals digestive tract in the center of the abdomen. Mature larvae are about 3 mm (1/8 inch) long. When
hundreds of these larvae congregate together to form a ribbon-like mass it is indeed an unusual sight in a landscape. Darkwinged fungus gnat larvae feed on the roots of many different plants and organic matter in the United States. They are recognized as important pests in greenhouses and mushroom cellars. They are also pests of houseplants. Adults and larvae inhabit moist, shady areas. Adults are very small, sooty gray or nearly black, long-legged, slender flies that live about 1 week. Females deposit 100-300 eggs on soil, usually near the base of plants. Larvae reach maturity in about two weeks and then construct a pupal case in soil. There is no reason to treat these masses of darkwinged fungus gnat larvae. Use this unusual insect behavior as an opportunity to educate your clients regarding the diversity and importance of insects in their landscapes.”

Daniel, thanks so much!  This is my second request over the years and I continue to be impressed with your skills and your website.
I just made a $10 donation to support your website; … .
All the best!  -John
PS: I’m looking forward to sharing the fungus gnat info with my NC friend when I see her soon.

What's That Bug? does not endorse extermination
Location: North Carolina

3 Responses to Aggregation of Fungus Gnat Larvae

  1. Terri says:

    I too have just witnessed this occurrence for the last two days, early in the morning. The masses of worms moving in a group and after speaking with NC agriculture people have been told the same – Fungus Knat Larve = Gross….. I had at least 8 to 10 clusters of these worms – couldn’t kill them all the 1st day with “Home Defense” spray. Second day I tried household cleaner – Tilex and that worked. These masses were at the edge of my grass and sidewalk or grass and concrete driveway. I have never witnessed anything like this.

    Thanks for you help in identifying these things….

  2. Ivy says:

    Thank you! I have 2 masses outside in the gravel bed bordering my back patio this morning. My cats & I have been entertained by watching them move around. I’m in PA, in the Philadelphia area suburbus.

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