San Antonio Express News
Sunday, May 11, 2003
By Nathan Riggs
Many calls have come in to the Bexar County Extension office over the past week on a variety of topics. A couple of them have been especially interesting and deserve some mention for this week.
Quite a few folks across the area have been alarmed by the sight of small green or brown worms rappelling down silk threads from their oak trees. These small caterpillars feed on the tender new oak leaves and blooms in the trees. Once they are full grown, the worms plunge from the tree on silk threads and find a nice, secluded place in the ground to spin a cocoon and become an adult. The adult stage is a small tan to yellow moth that is sometimes seen fluttering among the leaves of the trees.
The Buck Moth caterpillar allso feeds on oak leaves and are heading to the ground to spin cocoons. The only problem with these worms is that they are armed with stinging spines. Buck Moth caterpillars have a maroon-colored head and a body with purplish and cream-colored longitudinal stripes. Their bodies are covered with tufts of black, yellow and white spines, each capable of injecting painful venom, if touched. These caterpillars are way too big to be killed by regular Bt insecticides and must be killed individually by squashing them (shoes on, please!) or with insecticide sprays. The adult Buck Moths emerge in the fall and lay their eggs on the trees to wait for spring’s new leaf growth.
Another critter that has received a bit of attention is the spider mite. (See photos at top)Spider mites flourish in hot, dry conditions. They are named for the webs they make on their host plants while feeding. Spider mites usually feed on the undersides of the leaves and cause a stippled bronze coloration on the leaves. Treatments range from permethrin sprays to insecticidal soaps to neem oil or orange oil products. Strong streams of water and liquid seaweed fertilizers have also shown some effects on these tiny sapsuckers.
Spring in San Antonio is never the same from one year to the next. So much of our spring depends on winter conditions and rainfall that we never know whether we will feast or famine. One thing is for sure: there will always be insects and other critters waiting for those green leaves, gardens and flowers to hit their peak. Fore more information on Buck Moths and other stinging caterpillars, go to the Landscape Pest section of the Bexar County Extension website at http://bexar-tx.tamu.edu.
This article was written by Nathan Riggs, Extension Agent-IPM for Texas Cooperative Extension in Bexar County. For more information please call 210-467-6575.