It is not cross-pollination/fertilization. Had a cross occurred, you wouldn't see the result unless and until you saved the seed and planted them and grew them out.

Generally when zucchini is deformed it is either poor pollination or a viral disesase.

In terms of pollination, the flowers must be visited by multiple pollinators in one day in order for complete pollination/fertilization to occur. If only 1 pollinator made 1 visit, you can get deformed fruit like you described.

In terms of viral disease, there are several viruses that affect cucurbits. Some of them can cause deformed fruit. One of the more common viral diseases that can cause deformed fruit is zucchini yellows disease. Another would be one of the mosaic diseases, likely cucumber mosaic.

Dawn

Well thus far evey thing seems very disease free so I guess incomplete fertilization is a good bet. There are a number of aborts as well . The one symtem of that which i found in reading is the non greening ,turning yellow on the lower half of the zucs.

Last year I did notice far fewer bees andbummble bees. Usulaly when i fetch the papper in the morning the Daturas are very busy but not this year.