Is a comma needed with present participle phrase?

Question

I'm not sure if I'm using the correct terminology in my subject line, but I'm trying to figure out why the following two sentences do not seem correct to me:

1. But, if the larva is female, then it could become a worker having many jobs or an egg-laying queen.

2. He leaves his egg and is fed royal jelly by average females called workers for the next three days.

In the case of number 1, I feel drawn to setting off "having many jobs" with commas, but it doesn't seem right because this is an essential part of the sentence. Is the sentence fine as written or is there another reason it may feel "off" to me that I'm unable to name at present?

On number 2, it's the "called workers" part of the sentence that is bothering me. Again, I'm drawn to setting it off with commas, but it is essential, so that can't be right. I guess the sentence just feels too cluttered and confusing without some sort of pause for clarity in between. I need to explain the proper grammar to a student, but have been unable to pinpoint why these two sentences don't feel quite right.

Answer 1

Sentence 1: But, if the larva is female, then it could become a worker having many jobs or an egg-laying queen.

The noun "worker" is post-modified by the reduced relative clause "having many jobs". The clause can be expanded to "that is having many jobs". And here is the problem. Namely, the continuous form of "have" is generally only used in actions. For example, He is having a shower. She was having breakfast.

The continous form of "have" is not used for possessive relationships: *I am having two brothers. *The worker is having many jobs.

To fix the sentence, expand the noun phrase to "a worker that has many jobs" or replace "having" by "with".

Sentence 2: He leaves his egg and is fed royal jelly by average females called workers for the next three days.

There is nothing ungrammatical here. But for me the sentence reads slightly better if you reposition "for the next three days" as follows:

• He leaves his egg and is fed royal jelly for the next three days by average females called workers.

The end-position of "by average females called workers" gives it more "weight" than "for the next three days".

Answer 2

There is a clumsiness in the first sentence: when so much information is crammed into a sentence, great care needs to be taken in its construction. One could possibly argue that it is not clear whether 'having many jobs' is (a) defining (/restrictive/identifying) or (b) not:

• (1a) But if the larva is female it could become either a worker, and indeed a worker having many jobs – or an egg-laying queen.

• (1b) But if the larva is female it could become a worker (and these have many jobs) – or an egg-laying queen.

The lack of a comma after 'worker' in the original argues for the defining usage, but this seems an unlikely reading. I'd use whichever rewrite, 1a or 1b, is appropriate.

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With the second sentence, again a reformulation will be an improvement:

• (2a) He leaves his egg and is fed royal jelly by typical females (called 'workers') for the next three days.

• (2b) He leaves his egg and for the next three days is fed royal jelly by typical females called 'workers'.

In this case the rewrite is hardly essential, as the females which for the next three days are called 'workers' reading is highly improbable ... but sometimes it's better to avoid humorous even if unlikely alternatives.

I've changed 'average' to 'typical' as the notion of averaging one queen say and millions of workers is again better avoided.