Is this some form of mildew?

[RichH]

Looks like spider poop

Eyed spiders ... those that dont build webs .... usually patrol a territory in a routine pattern. This one seems to like crawling along the teak board where its crapping.

Other possibilities.
Artillery fungus, usually found after long rain/humidity will be more 'equally distributed'.

Midge emergence. If this happened at the time a 'new moon' then its probably the residue of emerging non-biting midges. These midges usually emerge on moonless nights along the mid-atlantic and either vomit a green blob or crap similar to what you see. But be careful as these midges are linked to 'vibrio' (cholera) so you want to wash your hands when cleaning up this 'crap' if it is from these midges. On some moonless nights there will be zillions of these midges on the surfaces of a boat. The green stuff does not release from woven dacron sails .... use a sailcover if youre in such an area. Bohemia & Sassafras Rivers on the Chesapeake is notorious for such emerging midges in April, May and earlly June. If the 'dark green blobs' dry out they become almost impossible to remove from gelcoat.

From your pic my bet is on crap from an eyed 'running' spider .... common wolfspider, beaded jumping spider, (extremely poisonous) brown recluse, etc. etc.

 

[Dan Johnson]

Hey Ross!

A couple of years ago if I had as many flys pooping on my house as there were black marks, I would have moved! Artillery fungus was the local diagnosis.

RichH's "eyed spiders" may be the cause inside the boat with no webs. I'll be scrubbing all the spots on the deck again by hand with SoftScrub this weekend to get rid of all the spider droppings that have accumulated over the past two weeks under all the webs they've woven. The worst ones are from spiders with bodies bigger than my thumb--scary buggers!

 

[Ross]

Links

Number 1 http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/gp1.htm.

#2. http://www.ridmax.com/flies.htm

#3. http://www.pestcontrolpa.com/index.php?pr=Spider

 

[Roger]

if they are spider droppings use a product called

Spiderban. It is a spray and our marina must be spider central because they are everywhere unless you spray with this stuff. I also got those similar marks on my sailcover as well as my deck. They came off with a power washer.

 

[Manny]

Cicada Killer Wasps

Wow Ross! There is another person in the world that knows what they are! I am one of the poor souls that has an infestation on my property. It's a shame really since they are so harmless to humans and animals, but they do unbelievable damage to my yard. By the end of August my front yard is covered with the little volcanos they create. I spend countless hours each summer trying to eradicate them but I can't seem to win (although each year it gets a little better). My next door neighbor is really meticulous about his yard and I try to keep them from going over. It is amazing to see them fly down from the trees carrying the paralyzed cicadas and flying into their dens. They lay their eggs inside the cicadas which then become nourishment - it's kind of ghastly really.
Allan R, your right about the spiders, it is really amazing how many there are. After cleaning the boat they are back within a few hours, by next day it's worse than before cleaning! Some massive ones hanging around. I'm going to put them to work as crew!

Oh yeah, back to the original question. Definitely looks like spider poo.

Manny

 

[CalebD]

Isopropal Alcohol will discourage many pests.

For a while. If you really want to get them off you boat light the stuff on fire for a few seconds and blow it out.

 

[Cap't Ron]

La Cook-a-racha!

Had the cockroach problemo aboard and in the tropics it can be hell when they get into one's stores.

Well, the fellow cruiser mates have a remedy for everything inclding urine for nematecyts (man-o-war) but keeping a supply of meat-tenderizer works best for these.

My memory says boric-acid?? Not sure but we did mix it with flour and milk in small balls then left it scattered round the vessel....

I was sceptical, but then it worked. No more roaches, like magic and we had tried the bug-bombs et al.
No, this is not a spider-shit tactic you fellows were talking about, but my knee is bothering me tonight and can't sleep mates....;-)

Maybe someone will remember the specific acid that was used in the POISON ROACH TRAP MIX. It may not be borac-acid, if I find out I'll post it when I return.

 

[Ross]

Manny just sweep the piles of dirt away. They (the wasps)

like the texture of the siol in your yard. Over seed and fertilize so as to get a thicker grass cover and they will do their digging elsewhere.