Get List of connected USB Devices

Adel Hazzah's answer gives working code, Daniel Widdis's and Nedko's comments mention that you need to query Win32_USBControllerDevice and use its Dependent property, and Daniel's answer gives a lot of detail without code.

Here's a synthesis of the above discussion to provide working code that lists the directly accessible PNP device properties of all connected USB devices:

using System;
using System.Collections.Generic;
using System.Management; // reference required

namespace cSharpUtilities
{
    class UsbBrowser
    {

        public static void PrintUsbDevices()
        {
            IList<ManagementBaseObject> usbDevices = GetUsbDevices();

            foreach (ManagementBaseObject usbDevice in usbDevices)
            {
                Console.WriteLine("----- DEVICE -----");
                foreach (var property in usbDevice.Properties)
                {
                    Console.WriteLine(string.Format("{0}: {1}", property.Name, property.Value));
                }
                Console.WriteLine("------------------");
            }
        }

        public static IList<ManagementBaseObject> GetUsbDevices()
        {
            IList<string> usbDeviceAddresses = LookUpUsbDeviceAddresses();

            List<ManagementBaseObject> usbDevices = new List<ManagementBaseObject>();

            foreach (string usbDeviceAddress in usbDeviceAddresses)
            {
                // query MI for the PNP device info
                // address must be escaped to be used in the query; luckily, the form we extracted previously is already escaped
                ManagementObjectCollection curMoc = QueryMi("Select * from Win32_PnPEntity where PNPDeviceID = " + usbDeviceAddress);
                foreach (ManagementBaseObject device in curMoc)
                {
                    usbDevices.Add(device);
                }
            }

            return usbDevices;
        }

        public static IList<string> LookUpUsbDeviceAddresses()
        {
            // this query gets the addressing information for connected USB devices
            ManagementObjectCollection usbDeviceAddressInfo = QueryMi(@"Select * from Win32_USBControllerDevice");

            List<string> usbDeviceAddresses = new List<string>();

            foreach(var device in usbDeviceAddressInfo)
            {
                string curPnpAddress = (string)device.GetPropertyValue("Dependent");
                // split out the address portion of the data; note that this includes escaped backslashes and quotes
                curPnpAddress = curPnpAddress.Split(new String[] { "DeviceID=" }, 2, StringSplitOptions.None)[1];

                usbDeviceAddresses.Add(curPnpAddress);
            }

            return usbDeviceAddresses;
        }

        // run a query against Windows Management Infrastructure (MI) and return the resulting collection
        public static ManagementObjectCollection QueryMi(string query)
        {
            ManagementObjectSearcher managementObjectSearcher = new ManagementObjectSearcher(query);
            ManagementObjectCollection result = managementObjectSearcher.Get();

            managementObjectSearcher.Dispose();
            return result;
        }

    }

}

You'll need to add exception handling if you want it. Consult Daniel's answer if you want to figure out the device tree and such.

  lstResult.Clear();
  foreach (ManagementObject drive in new ManagementObjectSearcher("select * from Win32_DiskDrive where InterfaceType='USB'").Get())
  {
       foreach (ManagementObject partition in new ManagementObjectSearcher("ASSOCIATORS OF {Win32_DiskDrive.DeviceID='" + drive["DeviceID"] + "'} WHERE AssocClass = Win32_DiskDriveToDiskPartition").Get())
       {
            foreach (ManagementObject disk in new ManagementObjectSearcher("ASSOCIATORS OF {Win32_DiskPartition.DeviceID='" + partition["DeviceID"] + "'} WHERE AssocClass = Win32_LogicalDiskToPartition").Get())
            {
                  foreach (var item in disk.Properties)
                  {
                       object value = disk.GetPropertyValue(item.Name);
                  }
                  string valor = disk["Name"].ToString();
                  lstResult.Add(valor);
                  }
             }
        }
   }