If you look closely, his leg is trapped on the dead bug and he's struggling! You can do it!
Don't give up!
If you look closely,
よく見ると
his leg is trapped on the dead bug and
(彼の)足が虫の死骸に挟まって、
he's struggling.
もがいているんだ!
If you look closely, his leg is trapped on the dead bug and he's struggling!
この様子にはアリを "he" と呼ばれるのが普段です。"trapped" とは 挟まっていて抜け出しにくい と言う意味です。
この際の「頑張れ」とは "You can do it!" 「できるよ!」とか "Don't give up!" 「諦めないで!」が良いです。