Weakling
Coward
noun, な adjective, の adjective
A weak insect. This is what people call weaklings in Japan. This is a good word to know if you're a bully, or something.
よわむし
The reading for this one is a weird one. It uses the kun'yomi readings for both, meaning you'll have to pull your knowledge of the word 弱い from earlier and apply it here. 虫 should be okay, though, as this is the reading you learned with the kanji.
Just remember, only weak bugs use kun'yomi, and that weak bug is you in this instance.
あんなに弱虫でなき虫だったむす子も、もう一人前の大人です。
My son, who was such a weakling and a crybaby, is already an adult.
多くのアメリカ人はなっとうごときが食べられない弱虫です。
Many Americans are cowards who can't even eat a bit of natto.
弱虫毛虫は、挟んで捨てろ！
Cowards should be treated like hairy caterpillars - picked up and thrown out!