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Common Name: Billbugs Scientific name: Sphenophorus spp.
Billbugs, also called snout beetles, belong to the beetle family Curculionidae (weevils) and are a relative of the rice water weevil. They complete one generation per year. Adult billbugs are dark gray; they overwinter under grass clumps, in leaf litter, and other protected areas in the soil. In the spring, they feed near the base of young rice plant. Females deposit their eggs in the stem at or below the surface of the soil. Developing larva feeds within the stem close to the soil. The larvae (grubs) are tan white colored, legless with a curved body. They are about ½ inch long and have a red-orange head capsule. They feed for several weeks, and then they pupate. The pupal stage is when the grub changes into the billbug adult.
Damage caused by adult: Billbugs injure multiple crops such as corn, sugarcane, wheat, rye and barley. Occasionally, it can be found in rice. Adults feed near the base of young rice plants. Their chewing mouthparts are found at the end of a long “snout.” Billbug feeding injures the heart of the tiller, causing death of the new leaf, or deadheart. Adult billbugs also injure the plants by cutting into the plant stem in which deposit its eggs at or below the surface of the soil. Larvae feed within the stem and in the main root close to the soil. The larval feeding injury can cause deadhearts and whiteheads. (Satterthwait, 1919)
Facts: Billbugs may occasionally attack rice in Louisiana. Adults and larvae both can injure rice.
What should you look for: To scout for billbug adults in drill-seeded rice fields, locate dying seedlings with deadhearts. Look for adults feeding or laying eggs at or below the soil level. The larva is also a damaging stage of the insect. Symptoms of larval feeding resemble those of borer injury, dead or dying leaves or whiteheads (blank panicles). When the stem is split near the base, grubs can often be found inside the stem.
How you can manage billbugs: The numbers of billbugs in a single rice field are usually below the level justifying insecticide treatment, but they may increase rapidly under favorable conditions and stand losses can occur. Contact your local cooperative extension service for control recommendations if you are experiencing stand loss due to a billbug infestation.