What is this verb form? 鳴きやんだら

Question

From よつばと！vol. 1 ch. 6 p. 15:

ジャンボ：　近｛ちか｝づく途中｛とちゅう｝で　鳴｛な｝きやんだら　警戒｛けいかい｝してるんだ　その時｛とき｝はじっと　鳴｛な｝き出｛だ｝すのを待｛ま｝つ

This is translated in the English edition as such:

If it stops buzzing as you approach, that means it's looking out for you. So wait until it's buzzing a lot before you try and catch it.

I understand 鳴｛な｝きやんだら is 鳴く (sing), but how do you get from the dictionary form to that?

By the way, I would appreciate if you could also give a more literal translation of the sentence.

Answer 1

鳴きやんだら

It's a hypothetical form of 鳴きやむ, "stop buzzing/chirping".
(The だら is the hypothetical form of the auxiliary た.)
鳴きやむ is a compound verb consisting of 鳴く + やむ(止む).

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A more literal translation would be like...

近づく途中で -- while [you are] approaching
鳴きやんだら -- if [it] stops buzzing,
警戒してるんだ -- it's that [it] is being cautious.
その時は -- in that case,
じっと -- patiently / quietly / standing still
鳴き出すのを待つ -- [you] wait for it to start buzzing.

Answer 2

なきやむ【鳴き止む】 means "to stop crying" (for an animal)
http://dictionary.goo.ne.jp/jn/163651/meaning/m0u/%E9%B3%B4%E3%81%8D%E6%AD%A2%E3%82%80/