From UNH Extension:

The sunny yellow flowerhead of the common dandelion is a familiar sight in New Hampshire lawns. Although long regarded as a pervasive weed, it has gained more positive attention in recent years for its potential to provide an early spring food source for generalist pollinator species. But does it? 

The Movement to Support Pollinators 

A popular “No Mow May” movement started in the UK to encourage people to hold off cutting their grass to let the weeds flower and provide food for insects, like bees, hoverflies, beetles, and butterflies.  Dandelions certainly have some weedy traits, taking over if left unchecked, but research suggests it may not be as beneficial to pollinators as some people believe.   

Not all flowers are equally good for pollinators 

Researchers have found that dandelions don’t provide a particularly good quality pollen when compared to other early-flowering species. In some ways they are like junk food. Experts found they are inadequate as a sole food source. Insects mostly feed on them because dandelions are a convient source of nectar, and sometimes pollen. More nutritional native plants would be better for them. 

Before you kill a dandelion, consider where it is growing 

The importance of a dandelion to a pollinator depends on what other options are available. In mostly paved urban areas with low floral diversity, dandelions may be the best option for early-season insects. But in areas that have numerous and varied spring native flowers, their impact may be minimal.   

While dandelions provide some nutritional benefits to spring insects, they are part of a broader ecosystem of flowering plants that collectively support pollinators. Homeowners who maintain a diverse floral landscape throughout the year provide the greatest benefits.