Do dragonflies eat algae and crickets?

"Agile Predators Dragonflies specialize in different kinds of hunting techniques. The larva stage is characterized by three basic strategies. Some stalk their prey in vegetation (climbers). Others lie in the mud and debris at the bottom of a pond and wait for prey (sprawlers). One species burrows itself completely in the mud (burrower). While the prey of the larvae is mostly other aquatic insects, some of the larger nymphs attack tadpoles and small fish. The adult dragonfly is a formidable hunting insect. Incredibly agile, it uses the basket formed by its legs to catch insects on the fly. It eats mainly mosquitoes, midges, and other small flying insects.  more

Nope. They eat mosquito larvae when they are newly hatched, and in adult form they eat any bugs at all.  more