larvae (I think), gray-brown, hundreds of them, most around 1 inch long, 1/4 inch diameter, have two little spikes at the back and a little head in the front.
January 19, 2010
Found after the rain under the carpet on front porch. I brushed them all off the porch. Today again hundreds of them under the rug. No idea where they come from. Cement porch meets soil on one side.
Van Nuys, California

Crane Fly Larvae: Leather Jackets

Hi Marianne,
The threat of a flooded habitat due to our Southern California series of deluges has caused the mass evacuation of these Leather Jackets from your garden.  Leather Jacket is a common name for a Crane Fly larva.  According to Charles Hogue in his wonderful book, Insects of the Los Angeles Basin, “The stout worm-like larvae (called leather jackets because of their thick dark skin) live in damp loose soil or leaf mold and feed on the root of herbaceous plants  In the spring, when such food supplies and moisture abound, large larval populations may develop and produce swarms of adults.”  The adults look like giant mosquitoes, but they are harmless.  BugGuide has numerous images of Crane Fly larvae, but nothing that resembles your phenomenal aggregation.

Crane Fly Larvae: Leather Jackets

Thanks so much. I hope as many as possible survive the “flood”. They look pretty ugly, but I googled a picture of an adult, and I think they are very beautiful, so delicate.  It’s so great to have your site available! Thanks again.

January 22, 2010
Thanks for posting this!  I live in Canoga Park, and I too had literally hundreds of these worm like larvae on my back patio, trying to invade my home!  I am glad I was able to identify them!  –

Update:  NOT (see next comment) Invasive Species
February 2, 2010
Great work as always!  Just some info regarding leather jackets.
There are two invasive European Crane Flies on the loose here in the US and they are serious pests. Most crane flies are harmless but these larvae can cause serious damage to lawns and seedlings.  The post on January 21st is definitely one these pests spp.  It is not uncommon for invasive species to be found in large numbers.
We have both spp. here in Michigan.  Both are new state records for 2009.
Some of your earlier crane fly posts are the exotics spp. as well such as on Oct 20,2009 where you mentioned they are harmless ( not to humans yes but to plants).
The links below have good information and some ID keys as well.
Just thought your readers should know.
Faithful Reader
Brian Sullivan

Chen Young responds
February 6, 2010
Hi Daniel,
Good to hear from you.  I have looked both of the images and none of them are the introduced European crane flies.  Noticed the middle lobes of the larvae are very dark and sharp which is not the character for the European crane flies.  The middle two lobes of the European crane fly larvae are soft and flesh like.  I don’t have an image with me now at home but I will send you one Monday when I get to work at the museum.  By the way, we are having a big snow storm and everything is closed for that matter thus I don’t think I will venture out to the museum  to get the image.
As for adult flies you can also check here for comparison of the two species.  These two species have also been reported recently in Michigan, New York, New England states, and Utah.  It will eventually in Pennsylvania.
Okay, I will send you image of the European crane flies on Monday.

4 Responses to Leather Jackets evacuated in the rain

  1. Dave says:

    These are also edible.
    There are scattered reports of their consumption by Native American groups. I’ve never tried them, and I doubt that they’d be easy to mass produce — unlike, for example, soldier fly larvae that look fairly similar and which are extremely easy to “farm.”


  2. kruszn72 says:

    Thanks for posting this! I live in Canoga Park, and I too had literally hundreds of these worm like larvae on my back patio, trying to invade my home! I am glad I was able to identify them! -Rich

  3. Steph says:

    I live in NYC in a basement-level apartment. Yesterday I noticed a fairly large patch of muddy dirt (about 5 inches by 5 inches) near one of my doors. I’m very clean so I was taken aback by this random spot. I looked closer and there was, what I think, was one of the leatherjacket larvae in the midst of this mud. It looked to be dying because it was lying on it’s side and slowly contracting it’s body repeatedly. I am so confused about how it got there and where this mud came from. I saw no trail to indicate that it had crawled from some hole in the wall or whatnot. Any ideas what happened? Are leatherjackets even common in NYC?

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