请分析一下这句话中kill在这里是什么成分?或者who引导的从句中谓语动词是什么?"we owe a lot to birds and beasts who eat insects but all of them put together kill only a fraction of the number destroyed by spiders."

we owe a lot to birds and beasts who eat insects but all of them [put together] kill only a fraction of the number destroyed by spiders 过去分词做后置定语[被防在一起]
kill 是but后句子的谓语/who引导的定语从句中谓语动词是eat

三楼正解

We owe a lot to the birds and beasts who eat insects but all of them put together kill only a fraction of the number destroyed by spiders.
我们十分感激食虫的飞禽和走兽，但把它们加在一起，也只捕杀了蜘蛛所消灭的昆虫的一个零头
who eat insects 限制定语从句 eat做限制定语从句谓语
all of them (put together) kill
括号里面put together 过去分词结构 做后置定语
kill 是but从句的谓语
望采纳！祝学习进步！

kill是but引导的句子的谓语，和we。。。是并列的句子。who引导从句的谓语是eat

we owe a lot to birds and beasts （who eat insects）——这是宾语从句.
but后面是并列句.
all of them （put together后置定语,put是过去分词） kill（谓语）
only a fraction of the number destroyed by spiders.