I think this might be Dr. Orpheus by <PERSON>. This was published in 1969 and it's the second in a series of books <PERSON> wrote featuring the character <PERSON>.
Dr <PERSON> finds a future Earthworld caught in a double-destructive pincers between benign enslavement by the miracle drug Anagonon and hideous enslavement by invaders from a far galaxy. To meet this twofold threat, <PERSON> must exercise his amazing abilities to the fullest, resorting to time travel, mind transfers, and a breathtakingly swift shell game of body transpositions, all the while battling the greatest odds he has ever faced.
As I recall <PERSON> <PERSON> books are all a bit weird even for 1969. The protagonist <PERSON> is some kind of advanced human who can travel in time and occupy different bodies. There is an invasion fleet from the Mandomen Galaxy, though as you say it hasn't reached Earth yet, and the ovipositor bearing aliens are the Myrons:
The masculate Myrons of Mandomen Galaxy were a breed that Mandomen mammals found peculiar, although an intelligent insect on Earth (if any had evolved) would merely have found them normal in a different way. Myrons, who were not insects but decapods, had by birth three sexes: male, female, and masculate. The females were the brooders, the mystique centers of clans, the rulers: queens and princesses. 322
The males were the fertilizers, rather stupid, strong in only one respect and otherwise weak.
The bracelets behave as you say, and the invaders plan to seize Bracelet One, which controls all the others. <PERSON> defeats the invasion by obtaining Bracelet Zero:
“Perfectly. But now tell me about Zero.”
“About Zero?” The German sat up straight. The gynecologist was frowning, puzzled. The other seven merely continued their attitudes of intense involvement.
“Yes,” <PERSON> insisted. “What about Zero in the Pythagorean arithmetic?”
Beginning to tremble again, the guilt-ridden psychiatrist ventured: “Zero did not appear in the Pythagorean arithmetic.”
“Why not?”
“Because Zero was not known until it was introduced into the algebra by Arabic philosophers nearly fifteen hundred years later—”
“And if <PERSON> had comprehended the number Zero—what rank would he have assigned it?”
The silence was intellectually and emotionally loaded.
The German internist fired a reply like a machine gun volley. “The question should be put a bit differently. If <PERSON> had lived today, and if in the light of all our knowledge he had projected his mystical system, which he might well have done: then how would he have ranked the number Zero? I say he would have recognized Zero as the number of psi-space, the number of ancient Egyptian Nun, the formless male-female progenitor of all the gods: the root of our word non. <PERSON> would have accorded Zero a rank higher than One, higher than Alpha—the ultimate rank, with no higher rank possible!”
That was when <PERSON> exhibited his bracelet. 417