To keep on or take off row covers off zucchini

Hi everyone. This is my first post! I've just recently started teaching a garden club at my school but I don't know anything about gardening. It has been an up and down journey but I love it. I currently have 6 zucchini plants under tule row covers because they were getting attacked by butterflies. I've used BT twice on them and the caterpillars are for the most part under control. A few of the plants have started producing male flowers for a couple weeks now but no female flowers have followed (not that I could identify). How long does it take for female flowers to show up? Anything I can do to encourage female flowers? I will be going out of the country for a week in two days and I want to know if I should leave on the row cover or take it off in hopes that female flowers will appear and pollinzation can take place. My plan was always to hand pollinate but obviously I can't if I'm not here. If I leave them covered for a week and return to female flowers, can I hand pollinate then or would it be too late? Thanks for any help :)

ive learned through the great minds here at DG that zucchini and all other plants in that family always produce male flowers first (i assume as a means of attracting pollinators, so that they will already be there for it when it starts producing the female flowers). But since you are hand pollinating yourself, that part wont matter ;)

as long as the flowers have not faded or wilted, and still look good, they could be fair game for hand pollination, i would think.

I personally have never gone by the row cover method (for lack of willingness to, to be honest), and i dont seem to have much luck at hand pollinating (but that is just MY personal experience), i usually let the bees around here do that job, and i have other flowering plants nearby to help draw in those pollinators.

I know that the idea of a plant being naturally pest repellent is an unproven theory, but the idea of pairing flowers that have said claimed properties beside of vegetable plants still will provide some diversity, thereby not making it such a red neon "Free buffet" sign, that a mass single planting of just one type of plant does, not to mention it makes the garden look more fun, in my opinion

http://www.andersonpestsolutions.com/green.php

Thanks for your response! I don't mind taking the row covers off for pollination I'm just so scared that those white butterflies/moths will lay a 100 eggs and I'll return to a caterpillar infested crop and have to spray bt again which is a bit time consuming. I definitely want to add some flowers to our garden as you've suggested so I will be picking up some seeds soon :) The male flowers seems to be fine but they are always closed, is that okay?

if they are closed, as if they havent yet opened up yet, then they should be ok, but if the petals have gone limp and raggy, then they have gone past their prime.

White "butterflies" sounds like cabbage looper to me, Do they have a black dot on their wings?

Planting dill, fennel, coriander and sweet alyssum, attract the kinds of insects and other creatures that prey on the caterpillars. If you see any caterpillars that look like they have white round dots attached to them, leave those alone as there is a predatory wasp that lay their eggs on the cabbage looper caterpillar, and will literally feed on it from the inside out.

To deter pests, I would keep the row covers on while you are gone.
The plant ought to keep on producing flowers until some get pollinated, then as you harvest the fruit the plant should produce more flowers