如果是正常的搜索引擎蜘蛛访问，不建议对蜘蛛进行禁止，否则网站在百度等搜索引擎中的收录和排名将会丢失，造成客户流失等损失。可以优先考虑升级虚拟主机型号以获得更多的流量或升级为云服务器（不限流量）。 更多详情请访问：　http://www.west.cn/faq/list.asp?unid=626 

蓝色部分是不明蜘蛛名称，根据需要添加，以|为分割。

Linux下 规则文件.htaccess(手工创建.htaccess文件到站点根目录)

<IfModule mod_rewrite.c>
RewriteEngine On
#Block spider
RewriteCond %{HTTP_USER_AGENT} "SemrushBot|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|curl|perl|Python|Wget|Xenu|ZmEu" [NC]
RewriteRule !(^robots\.txt$) - [F]
</IfModule>

windows2003下 规则文件httpd.conf　　　（在虚拟主机控制面板中用 “ISAPI筛选器自定义设置 "  开启自定义伪静态 Isapi_Rewite3.1 ）

#Block spider
RewriteCond %{HTTP_USER_AGENT} (SemrushBot|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|mail.RU|curl|perl|Python|Wget|Xenu|ZmEu) [NC]
RewriteRule !(^/robots.txt$) - [F]

windows2008下 web.config

<?xml version="1.0" encoding="UTF-8"?>

<configuration>

    <system.webServer>

        <rewrite>

            <rules>

<rule name="Block spider">
      <match url="(^robots.txt$)" ignoreCase="false" negate="true" />
      <conditions>
        <add input="{HTTP_USER_AGENT}" pattern="SemrushBot|Webdup|AcoonBot|AhrefsBot|Ezooms|EdisterBot|EC2LinkFinder|jikespider|Purebot|MJ12bot|WangIDSpider|WBSearchBot|Wotbox|xbfMozilla|Yottaa|YandexBot|Jorgee|SWEBot|spbot|TurnitinBot-Agent|curl|perl|Python|Wget|Xenu|ZmEu" ignoreCase="true" />
      </conditions>
     <action type="AbortRequest" />
</rule>

            </rules>

        </rewrite>

    </system.webServer>

</configuration>

注：规则中默认屏蔽部分不明蜘蛛，要屏蔽其他蜘蛛按规则添加即可
附各大蜘蛛名字：
google蜘蛛：googlebot
百度蜘蛛：baiduspider
yahoo蜘蛛：slurp
alexa蜘蛛：ia_archiver
msn蜘蛛：msnbot
bing蜘蛛：bingbot
altavista蜘蛛：scooter
lycos蜘蛛：lycos_spider_(t-rex)
alltheweb蜘蛛：fast-webcrawler
inktomi蜘蛛：slurp
有道蜘蛛：YodaoBot和OutfoxBot
热土蜘蛛：Adminrtspider
搜狗蜘蛛：sogou spider
SOSO蜘蛛：sosospider
360搜蜘蛛：360spider