Did a quick DDG (fug google) search.
Hand pollination increases success. Also will have to refresh knowledge of blossom anatomy.
Zucchini plants (Cucurbita pepo) thrive in locations that receive full sun and have well-drained, fertile soil with a pH of 6 to 7.5. They can be grown throughout the United States during frost-free months. Many inexperienced gardeners mistakenly think something is wrong when their zucchini plant produces flowers but no fruit sets. Zucchini plants produce male and female flowers, however, and only the female blooms produce fruit, which doesn't happen until the flowers are pollinated.
Zucchini Pollination Process
Zucchini pollination occurs when the sticky pollen from male flowers is introduced to female flowers. Zucchini plants do not have wind-blown pollen, notes the University of California Cooperative Extension Master Gardener Newspaper Articles.
Bees are the primary pollinators of zucchini plants, although other flying insects can be pollinators. When a bee visits a male zucchini flower, pollen from the flower's stamen sticks to the bee's hairy legs. When that bee visits the female zucchini flowers, its legs touch the flower's sticky stigma, which transfers pollen from the bee's legs to the stigma, completing pollination. The pollinated female flower shrivels and closes, and a tiny zucchini fruit at the flower's base begins to grow.
Zucchini Fruit Growth
The tiny zucchini fruit at a female bloom's base reaches 4 to 6 inches long within one week after pollination. Harvesting the fast-growing zucchini fruits when they are young and picking all the fruits from a zucchini plant encourage the plant to produce new blooms and prolongs its fruit production. If allowed to remain on the vine, a zucchini fruit quickly grows to its mature size of 1 foot or longer within a few weeks.
Zucchini Plant Hand Pollination
Sometimes, zucchini plants fail to pollinate because of weather conditions or a lack of pollinators. This is especially common in urban areas with smaller bee populations.
When that happens, pollinating by hand is necessary for the plants to produce fruit. Gathering pollen from the male flowers with a small, art paintbrush or cotton swab and depositing the pollen in female blooms is a simple task and pays off with an abundance of zucchinis, advises the University of Florida IFAS Extension.
Alternatively, you can pick a male flower and remove the petals. Once the pollen is exposed, roll it on inside the female flower to transfer the pollen. Pollination is best done in the morning when the flowers open.
Male vs. Female Blooms
Identifying the male and female blooms is the first step toward hand pollinating them. Male blooms appear on a long, slender stem. When you remove the petals, you will see an anther with bright orange-yellow grains of pollen. The first flowers to appear on the zucchini plant are male flowers.
Female blooms, however, are closer to the base of the plants, and each female bloom has a miniature zucchini fruit at its base. If the female flower is pollinated, the tiny fruit begins to grow into a full-size fruit. If the flower is not pollinated, the tiny fruit shrivels and drops from the plant.https://homeguides.sfgate.com/pollinating-zucchini-do-62656.html