Dr. Dan Suiter (UGA Extension Entomologist) explains why cockroaches are the only insects that keep their excess nitrogen instead of excreting it, why that makes an American cockroach survive three months on water alone, and why it makes the large roaches take bait so readily. He covers peridomestic harborage, granular bait versus residual spray, a paint can trap baited with beer-soaked bread, and German cockroach reproduction.
Structural Pest Control series, recorded November 10, 2021. Runtime about 55 minutes.
CEU categories for this archive are pending confirmation. Check with the UGA Center for Urban Agriculture before claiming credit.
Chapters
0:00 Welcome: cockroaches of the Southeast
1:54 ESA credentials: ACE, BCE, and the new CIT
7:39 Food and water: surviving on water alone
10:20 Nitrogen, uric acid, and the cockroach fat body
17:42 Gout, allopurinol, and a patented use
20:52 Peridomestic roaches and the true palmetto bug
23:48 Harborage: warm, humid, still, and dark
26:29 Half-starved roaches, bait, and egg case wasps
29:27 Smoky brown roach: egg capsule to first instar
31:35 Tree holes, soffits, and block wall voids
36:05 American roaches, sewers, and the old bait pastes
41:48 The paint can trap: mineral oil, beer, white bread
44:26 Gel bait in the field, and fire ant secondary kill
47:10 German roaches: food and water are never limiting
49:22 Reproductive biology: gravid 75% of adult life
53:59 Crack and crevice, and the flashlight test
Questions Answered in This Session
How long can a cockroach survive on water alone?
A German cockroach goes more than a month on its fat body reserves; an American cockroach goes three. Give them food but no water and they last just short of two weeks, about the same as complete starvation.
Why are the large roaches so easy to bait?
They are half starved for nitrogen. Cockroaches hold onto excess nitrogen instead of excreting it as uric acid, so they forage for it constantly. Run a car over roaches at a manhole cover and the survivors come back out minutes later and eat the squashed ones, going straight for the uric acid.
Why use granular bait instead of a residual spray outdoors?
A pyrethroid microcap works, but it also kills the tiny wasps that sting cockroach egg capsules. About half the capsules in Suiter’s Florida study had been stung. Granular bait leaves the wasps working and lasts far longer through weather.
I baited and the roaches came back. Why?
Egg capsules incubate for 40 days. The first application kills the adults; a second wave arrives when the capsules hatch.
How do I trap large roaches without pesticides?
A quart paint can, inside lip coated with mineral oil and Vaseline mixed one to one. Cheap beer soaked into white bread, in a small cup with screen over the top, set in the bottom of the can. Put it against a wall. Suiter has caught 75 adults overnight in one can.
Why does the gravid German cockroach female matter so much?
She mates once, produces six or seven egg cases, and is gravid about 75% of her adult life. During each 27-day gravid stretch she sits in a harborage and does not eat, drink, or move. Killing males does nothing, because she only mates once. Reaching her means aerosols in screw holes and bait in cracks.
Resources
entsoc.org: ESA certification programs (ACE, ACE International, Board Certified Entomologist, Certified IPM Technician)
Cockroaches of the United States: a distribution review by Tom Atkinson, published by the Entomological Society of America
Getting the Best of Pests, Structural Pest Control Series — UGA Center for Urban Agriculture