Are elders needed for worship services?

From the perspective of church governance, I would suggest taking a look at our church order.  There are a number of articles that talk about the duties of the minister, as well as the elders and deacons.  Article 52 states:

Article 52

a. The consistory shall regulate the worship services.

b. The consistory shall see to it that the synodically approved Bible versions, liturgical forms, and songs are used, and that the principles and elements of the order of worship approved by synod are observed.

c. The consistory shall see to it that if liturgical forms are adapted, these adaptations conform to synodical guidelines and that if choirs or others sing in the worship service, they observe the synodical regulations governing the content of the hymns and anthems sung. These regulations shall also apply when supplementary hymns are sung by the congregation.

The consistory is the name for the elders as a group.  The elders are responsible to make sure that each worship service is just that, a worship service, and one that adheres to Biblical teaxchings.  A worship service is not a one man or one woman show.  Worship is corporate. 

Could you have a worship service without an elder in attendance, sure, but it is not a good practive.  An elder or two should be at all worship services.

Thank you. We had a PM worship service recently where only 1 deacon was in attendance (running sound) and no elders. A member who had been an elder a number of times before but was not on consitory at present was deemed an honorary elder for the duration of the service by me (the pastor).

Some people make a distinction between an "official" worship service, and other gatherings.  At official worship services elders should supervise and attend.   If elders are not present, it will be an unusual circumstance.  If elders are absent without good reasons, then the church is likely sick.   But I agree that former elders or off-duty elders can be designated by consistory to fulfill that role of supervision and regulation, although it ought to be done preferably by the consistory/other elders and not by the pastor, who is after all being supervised ultimately.  

Ultimately it is the decision of the consistory whether a service can be held without an elder present.   It should be a conscious, not an accidental decision.