Dobson flies and Damselflies-Aquatic Garden Invaders

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Unusual insect visitors have been popping up in the garden the past few weeks -- mainly the Dobson fly and the damsel fly. There has been a report of Dobson flies congregating around bee hives by a local bee keeper and the lemon grass growing in my straw bale has become a haven for dozens of damsel flies.

Dobson flies are 2 to 3 inches large, brown and fold their delicately veined leaves down. The male of the species has menacing sickle-shaped mandibles but does not bite. The female has considerably smaller mouthparts and is capable of biting. They are believed to not eat, but entomologists have observed them eating honey water in captivity. They are short lived and only have one purpose; to procreate. The males are believed to use their large mandibles to fight off other males and holding down the female during copulation. They are most active at night, live in vegetation and rear up their head when threatened.

The females lay their egg clusters on tree leaves, rocks or bridges near water and cement them it in with a sticky substance that turns white when it dries and closely resembles bird droppings.

The larvae are brown aquatic predators and once they drop in the water of streams can live two to three years. They use leg hooks to hold onto the bottom of the stream and hide under rocks to eat other immature aquatic insects like caddisfly and damsel fly. They are able to breathe in and out of the water and they crawl to rocks or debris in soil to pupate. The adults emerge in mid-summer and are a good sign of biodiversity and a healthy ecosystem.

Damsel flies are a smaller and daintier version of the closely related dragon flies. They hold their wings closed over their bodies rather than straight out like a dragon fly. They are most known for the bright colors, aerial acrobatics and very large compound eyes. Females and males join into a wheel position when they mate. Damsel flies have pronounced jaws that lower and extend to capture prey like midges, small flies and occasionally mosquitoes. The aquatic larvae has a pronounced snout for stabbing and eating mosquito larvae and pupae.

To ensure visitors like these keep your garden and homes free of pests, plant trees, shrubs and flowers and allow habitat like fallen branches and rocks near the stream.