High Tunnel Insects

The thaw of March 11th was too good to be true; just in time for spring break, we had weather that lifted our winter-wearied spirits and painted smiles on faces all around. The high tunnels that morning smelled rich with spring soil and felt humid with the misty air. The plants looked happier then than they have for the whole of spring semester, and though the temperature has dropped again and the cold winds have risen, that morning was a sure sign that wintertime is crumbling.

With activity to rival that of the plants, the insects that have found refuge in the high tunnels during these cold months are flourishing. A few weeks ago, our expert entomologist and Insect Pest Management professor, Dr. Alan Eaton, was kind enough to come out to the high tunnels and give the class a tutorial on insect identification and management.

Alan Eaton giving fair warning that sticky yellow cards will 

grab long hair and fine clothing as readily as flying insects.

Our class explored the heated high tunnel looking for thrips, aphids, fungus gnats, whiteflies, shore flies, parasitic wasps, and the ambiguous "other," seldom identified because, as Dr. Eaton reminded us regularly, not everything in the greenhouse is a pest.

Our classmate Pete enjoying the world in 10X.

 A few insect identification tips for our readers:

Thrips (sing., thrips; pl. thrips) are tiny, dark-eyed, straight-bodied insects with straight antennae and a stature so small that their wings are composed only of fine hairs.

Photo of thrips on a marigold blossom.

Aphids are plump-bodied insects that cannot be properly identified based on color or presence of wings. There are many of species of aphids that dwell in greenhouses and high tunnels, and proper magnification is necessary for accurate identification. Look at the notch on the head of the aphid to determine what kind it is. White casts on plant leaves are a telltale sign of aphids. Copper colored aphids are actually aphid "mummies" that have been parasitized by wasps. 

Winged aphids will often give birth after getting 

stuck on yellow sticky cards. The parallel veins on

the wings are also characteristic of aphids.

Parasitic wasps are effective predators of aphids--female wasps lay their eggs in the aphids, which are eaten by the larvae, always orange in color, after they hatch. 

Aphidus colemani, a species of aphid wasp.

Fungus gnats are long-legged, thin-bodied, dark insects with y-shaped veins on their wings and long antennae. They thrive in wet media and feed on decaying organic matter, though they will often burrow into fresh cuttings and eat the inside of the stem. 

An adult fungus gnat on a sticky yellow card. 

Shore flies are perhaps the most distinctive of insects in the greenhouse; they have smoky wings with clear spots that appear white. No other insect has wings like these, so they are easily identifiable. They can be vectors for pathogens, but they are mostly a nuisance and can make greenhouses appear quite infested. Shore flies feed on algae, so controlling algae growth can be an effective preventative measure. 

An adult shore fly with the characteristic

spotted wings. 

A sincere thank you to Dr. Eaton for teaching us about greenhouse pests, and for providing these images to pass on to our readers! Until next time, keep an eye out for pests, watch things grow, and enjoy the coming spring! 

~Anne Howard

Photos and information courtesy of Alan Eaton, University of New Hampshire Entomologist.