Well, judging by the image on the right, the answer is yes. Ever since I put out the over ripe watermelon the bees have been all over it.
The nutrients contained in watermelon are attractive to honey bees. In fact, any fruit with moisture and sugar content are a major draw, especially during a dearth. Watermelon has a 92% water content which makes it appealing to our bees.
During the middle of the summer when nothing is blooming, the bees need to be fed. Your goal is to make your hives strong enough to survive the winter ahead.
Fruit is an excellent alternative to sugar water, due to the added nutrition. You can often go to local food markets to obtain cracked and spoiled watermelons free of charge. It may be a bit messy, but your bees will be thankful.