Why are some of the fruit on my summer squash misshapen?

Question:

Why are some of the fruit on my summer squash misshapen?

Answer:

Misshapen fruit may develop if pollination is inadequate.   When pollination is incomplete, the fruit develops unevenly because the ovary wall enlarges more adjacent to fertilized seeds.  Inadequate pollination may be due to low pollinator numbers or unfavorable weather.  

Virus infected plants may also produce small, deformed fruit.  Viral diseases cannot be controlled with pesticides.  If disease symptoms appear on just a few plants, remove and destroy the virus infected plants to prevent the further spread of the disease.