The Joy of Summer for Your Lawn
Chinch bugs,Chiggers, & Grub Worms

Chinch bugs:

The southern chinch bug, Blissus insularis, is one of the most important insect pests of St. Augustine-grass in Texas. Chinch bugs usually become a problem in the heat of summer and early fall. They are 1/16” to 1/5” long. Adults have black bodies with white triangular marks on their backs. Young are red with or orange with white stripes across their back and cause the most damage. Chinch bugs are a native and normal part of soil life. There are different species of chinch bugs that favor particular plants. In the urban south, they like seem to show up in St Augustine grass more, but others are a big problem with commercial crop plants too. They pierce the grass leaves with a needle like beaks and inject saliva that is toxic to the leaf. I think the slobber must breaks down the tissues for easier slurping. Anyway, both activities kill the grass blade.

The bugs don’t usually make as nice of a round brown spot in the grass as Brown Patch but can look more like the irregular spots from Take All Patch or drought damage. To tell the difference, you need to see the bugs. The bugs are found on the border of the brown patch where the grass is yellowing and are more active in the warming morning hours before 11:00 o'clock. You might be able to see them if you get on your hands and knees and stick your head into the grass. Sneak up on them as they will hide in the thatch. The classic technique is by cutting the bottom out of a coffee can, and pushing the can into a yellowed patch of grass in the sun, about two inches deep in the soil. Fill with water. If infested, chinch bugs will float to the top within five minutes. You can also sink a shovel-sectioned piece of grass and sod of the yellowing area in a bucket of water and see what floats to the top.

Sample for chinch bugs” byPhilip Busey:
Excerpt: Sliding-foot method. Interestingly, other sampling methods exist. A Mississippi State University Extension bulletin says, "You can readily find any chinch bugs by slowly sliding your foot through the sod and watching for the bugs to crawl across your shoe." That sounds easy enough. I have also noticed the distinctive, pungent odor of chinch bugs when I mow. It's not as reliable as other methods, but it has alerted me to stop and check for the bugs.

Chinch bugs should not be a problem in well cared for lawns. They like hot dry stressed grass and have said to be an indicator of poor lawn maintenance, watering in particular. They almost always start near concrete or rock walkways, sidewalks, driveways and such, where the grass dries out faster and becomes stressed if not watered. Proper watering, fertilizing, thatch control, and a healthy soil microbial environment that has lots of natural predators will control them. Dry warm conditions may lessen their control from diseases. A soil fungus, Beauveria spp., will kill off most chinch bugs in the wet cool part of fall. You may see it as a grayish cottony mass of fungal hyphae in the grass. Immediate control is to use D.E. around the brown area or spray with a compost tea, molasses, citrus oil mix like Howard Garrett’s fire ant drench formula (mix equal parts of each, then mix 4-6 ounces to one gallon of water). If you can't top dress the entire yard with compost, at least apply it where the chinch bugs attack to help hold the soil hold moisture longer.


Trombicula alfreddugesi (Oudemans), the common harvest mite or chigger.

It is said that chiggers are said to be a sign of poorly kept lawns. Properly watered lawns rarely have them. As a kid, the un-maintained alley was where you got them. I must admit, along with many of our customers, that you can still have them in nice lawns also. Chiggers are barely visible, naturally red mites that are normally vegetarians in the soil. Only the larva form wants to bite us. They actually want to bite reptiles and birds, but we will do. They like thin skin areas like on women and children and in skin folds or protected areas where clothing is tight. So the soft thin parts under tight underwear seem to be popular. They are fast too. They can go from ankle to waist in 15 minutes. They don’t borrow into your skin, but insert their mouth parts into your surface skin cells, and injects saliva that contains a digestive enzyme to dissolve the skin cells. This is what they slurp up, not blood. They alternate sucking and spitting to dissolve more of your flesh. The saliva is what causes the inching and inflammation, but this also happens because we are not the natural host. Human host chiggers in Asia and the Pacific Islands don’t cause inching (is this why they call it Paradise?). The chiggers here can feed for a few hours before you notice them. If you don’t scratch or wash them off, they can feed for 3, 4 days or longer. They are easy to brush off. If you can’t wash, use a dry towel to wipe them off if you think they are on you. Just don’t get paranoid and carry a towel around with you everywhere you go.

They are not ambush predators, but hunters. They are always scurrying around. To test for them in your yard, place black or white cardboard, dinner plate, or anything thin with a contrasting color to red, vertically in the ground. They will run up to the top and accumulate where you can see them easier with a magnifying glass. Laying the items horizontal will work, but the chiggers will not be concentrated for easier viewing.

Chiggers like the heat. They become inactive under 60 degrees and die at 42 degrees. They occur in patches around where they hatch in the spring. They don’t move far so they are not everywhere.

Immediate control is to Spread granulated sulfur around your yard where you find chiggers. For large areas, we have granulated sulfur in 50 pound bags that you can use in a fertilizer spreader at 5 pounds per 1,000 square feet. D.E.(diatomaceous earth)will work to control them too. Fill a cheap pillow case or two half full of D.E.. Tie off the opening (clove hitch with clothes line cord, holds knots well) to make a loop to drag around the yard. You can use the pillow case DE to lightly bounce off the floor indoors to dust for fleas. If it is cool enough, 85 degrees in the evening or less, horticultural oils will kill them. Cedar oil in particular will kill chiggers, fleas, ticks, and mosquitos and repel for a week or two.

To protect yourself powder puff with a sock of dusting sulfur around your shoes, socks and pant legs. Deet will repeal them for a few hours, but sulfur works better. In Boy Scouts, we soaked our pants and socks in wettable sulfur in the bathtub and line dried them. As I remember, this seemed to works for a few days, but we may not have gotten into a chigger nest either. The sulfur stinks though. The clothing optional lifestyle of some parts of our society, removes the tight fitting places chiggers like, but add the places mosquitoes like. Oils will kill them and I’ve read where some people use heavy doses of baby oil or herbal oils to keep them off. But those people probably like the slipping around in all that oil. To each his own.


Grubs may start to become a problem now. The newly hatched grubs are the grass root eaters in mid summer and fall. Beneficial nematodes are the best control. Nematodes are more likely to be available in the fall as they don’t ship well in the summer. Nematodes also do better in cooler, wetter soils. Under good conditions, nematodes may reduce white grub populations by 50% or more. One microbial pesticide, Bacillus popilliae, or milky spore disease, is often recommended for white grub (Japanese beetle) control in other regions of the U.S., but has not been shown to be effective against Texas turf-infesting white grubs. Spiked sandals sold for aerating turf have been tried with some success for controlling damaging grub populations. According to one study, repeatedly walking over heavily infested turf with the spiked sandals may reduce grub populations up to 50%. We don’t carry these sandals though.