Old House Borer

OHB Larva

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Old House Borer Larva



The head of the old house borer larva is round and is much larger than its tail, a shape which is typical of the Cerambycidae beetles which are known as "round headed borers." This larva is greyish-white in colour and grows from 2 cm to 4 cm in length. Female larva is significantly larger than male larva of the same age. The head capsule is dark brown, and three simple eyes are found on each side of the head when viewed from the front. This characteristic sets the old house borer larvae apart from other long horned beetle larvae found infesting wood. Other long horned beetle larva has only one such eye on each side of the head. The holes of the larvae are oval shaped. The frass of the old house borer consists of very fine powder and tiny pellets that are tightly packed within the galleries or hols.





Wood consumption in all larval weight classes was greatest in the temperature range of 20C to 30C, and significantly reduced below and above these temperatures. Inside that temperature range, larvae consumption of wood is greatest at higher temperature and higher relative humidity with less vary. Larvae consumption of wood in ideal environment conditions (29C 2C, 80 5% RH) is about 34 mg/larva per day, but significantly low at still very good environment conditions with greater deviations  (24C 10C, 76 9% RH), only about 12 mg/larva per day. Despite a significant difference between larvae weights they consume nearly the same amount of wood.





Developmental rates of Hylotrupes bajulus larvae are affected by extremes of temperature; medium and large larvae are affected to a greater extent by changes in temperature than small larvae.  Growth rates for small larvae were not significantly different among temperatures while medium and large larvae exhibited negative growth rates at 15C and 35C. The effects of temperature were evident in low and high respiration values for medium and large larvae at 15C and 35C. Respiration rates were highest for small larvae.





In pine softwood the activity is composed of single spurts, lasting from 5 to 180 min at a relative humidity of 73%, alternating with phases of almost complete inactivity lasting 5 to 25 min. They are getting more stable under temperature changes of 12 hours at 18C and 12 hours at 25C.