There is no joy afield when these flies are buzzing

It's a mystery, but much of the field corn I have seen in southern Minnesota is knee-high twice over. Still, more rain is badly needed in most areas.

Gardeners are picking raspberries and the first ripe tomatoes. Hollyhocks, daylilies and early hostas are blooming. Reports from far southern Minnesota to far north tell us that we are in the peak of firefly season. Too, people are seeing the first generation, after migration, of monarch butterflies. The common milkweed is blooming nicely and is fragrant.

Most lake water temperatures are in the 70s and perfect for swimming. I have encountered fewer mosquitoes on adventures this past month, no doubt because of the shortage of rain. But deer flies and horse flies continue to make outings less enjoyable.

The family of insects that includes both includes close to 300 species of these specialized flies. The females are bloodsuckers. Their mouth parts are developed for cutting skin and sucking blood that oozes from the wound. The ingested blood is rich in protein — needed to develop their fertilized eggs, so only females bite. The males feed chiefly on pollen and nectar and are often found on flowers.

The larvae of most deer and horse fly species are aquatic. Eggs are laid in masses on leaves and other objects that overhang the water in swamps, marshes or sluggish streams. After the maggots hatch, they drop into the water and stay in the bottom mud or sand, where they feed on snails, insects and other organisms. Life cycles are often a year long, but some species take up to three years for new flying adults to leave the water.

Horse and deer flies sometimes carry diseases. The bites are painful and can become infected.

Deer flies are a bit larger than house flies and have dark-colored markings on their wings. We encounter them near wetlands and streams, and on forest hiking trails, where they buzz around our heads and get into our hair. Deer flies only hunt during the day, with peak activity the three hours after sunrise and the two hours before sunset.

To protect yourself and your animals, read up on repellents, wear a hat and light clothing and check YouTube's "Get Rid of Deer Flies."

Jim Gilbert has taught and worked as a naturalist for 50 years.