My sister has a trailer and when it rains she gets maggots and I need to know how to stop that. I know I have to place wooden boards on the bottom of trailer and new boards and tiles inside, but where do we start and how can we do this easy and fast. Help Please.

Maggots? Maggots live in rotting flesh, not rotting wood. If you do have maggots then you have some form of vermin problem, maybe mice or other rodents that are also dying under your trailer. I would start with exterminating, either as a DIY project of by calling in someone who can track down what's going on. Once you get the cause of the problem solved than you can move on to fixing the trailer.

It's hard to seal a living space against something as small as a maggot - in fact it's just about impossible to keep something like a mouse out of your house, much less a trailer. Replacing subfloors and sealing all gaps with caulk could help, but again - without solving the original critter problem you will have little success.

If the original floor is screwed or bolted in place, begin by trying to unscrew/unbolt the floor so you can use them aganin to screw the new floor in place. If they won't unscrew then you may neet to drill them out and add new mounting points and screws to the frame of the trailer to hiold the new floor in possition.
Also, if you can keep the old floor in one piece then you can use it as a template for the shape of the new floor.

Maggots are fly eggs and can be laid in rotting food. Perhaps there's some food on the floorboards or underneath, brought in by a critter? Or maybe there's a dead critter there or underneath the trailer?

What doesn't make sense is why these insect larvae appear when it rains.

I'm wondering if they're really maggots or some other kind of insect larvae. You're sure they're not "pill bugs", which are attracted to moisture? That would make sense as rain could be an attraction for them.

I can't offer any suggestions on repair but I can suggest that you could spray the area with rubbing alcohol after rain to try to kill the insects that do appear. I spray it straight, undiluted, and it does kill even larger insects like yellow jackets. However, if there are masses of the maggots, you'd have to spray pretty heavily.

Good luck; this sounds like a very unpleasant situation and must make you and your sister uncomfortable.

Having just seen a nature documentary on stinging insects and their larvae, I wondered if the maggots you're seeing are actually the larvae of some insect that crawl out after rain because their nest or "living space" becomes wet.

Perhaps you could catch some (repugnant as that may be) and take them to a local agricultural extension service for identification.

Your post doesn't indicate your location, so I can't determine whether there are any agricultural colleges or extension services in your area. You could call your county government offices, perhaps the health department, and ask if they're aware of such an extension service.

get a crummy clear-ish bowl and a flat piece of sturdy plastic. a deli container and a scrap piece of glass or plexiglas are good. put the container over a nasty piece of floor. when the stinkers are crawling, tip up the container, and if some of the squirmies crawl up on the glass you slide under the edge of that container, slip it all the way under, turn the assembly upside down, tap the critters into the deli container and lock on the top.

take it to an exterminator or extention service office and find out what they are.

then you can find out how to take care of the issue.

if they're wood-eating stinkers, a complete solution is probably going to include replacing the subfloor in the trailer, and sealing the bottom.

The bottom of the trailer is all gone. She does not have insulation and wood or wherever goes under a trailer is all gone. From what I saw I first have to find someone to level her trailer first then add insulation and cover bottom of trailer then I can work with the inside. What do ya'll think

When you say "The bottom of the trailer is all gone", are you describing a small portion of the floor, an entire room or the entire trailer?

I think a high if not the first priority along with how to fix the missing floor is to determine how this happened in the first place so you can avoid it happening again and/or fix whatever caused the floor to collapase/rot, or whatever.

In the meantime, is there anything at all on the floor or in the trailer to secure it from the elements and critters that might decide to set up housekeeping?

I hope she has someplace to live until the trailer is fixed?

It seems to me this is an emergency situation with health and safety complications. Without prying, I'm thinking that perhaps your sister is not in a physical or financial position to fix the trailer but needs help.

If so, have you contacted the community goverment in the city/township/ which she lives to find out if they participate in any HUD or other subsidized home repair program? Many communities do, and from what I understand the priority of funds is allocated for health and safety issue repairs.

My community liaison told me that the funds are allocated annually, I believe in July, but that communities are at the pleasure of the federal government to disburse the funds and sometimes they're not available for a few months. But there may be some funds left from last year's allocation which might be available now.

Another thought is Habitat for Humanity but I don't know how long it would take for them to allocate resources for fixing the trailer.

If my assumption is wrong, I apologize.

I do wish you and your sister good luck in resolving this situation. It must be very unsettling and stressful for both of you.