Forest Practices Code - Terminal Weevils Guidebook

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Terminal Weevils Guidebook Table of Contents]

Glossary

Oviposition
Laying of eggs.

Chip cocoon
A pupal cell constructed partly in the bark but mostly in the sapwood by mature weevil larvae. This cell is oval in outline and is lined with excelsior-like shreds of wood fibre. These oval "cocoons" remain embedded in the wood long after the weevils emerge and are a characteristic feature of the genus Pissodes.

Crease
Minor defect comprised of a linear indentation but little or no stem curvature at point of attack.

Crook
A major defect, defined when a lateral assuming dominance is offset from the main stem by at least half the stem diameter. The most common major defect resulting from weevil attack is a crook.

Degree-day
A unit of heat. The equivalent of one degree of temperature, maintained for 24 hours, above or below any specified base temperature, e.g., 2 for 12 hours or 0.5 for 48 hours. Often used in predicting the time of incidence of insect pests in the spring. For purposes of plant growth and animal development, the base temperature may be the temperature above which growth can be initiated and maintained.

Fork
A major defect resulting when two laterals assume dominance.

Hazard An estimate of the amount of damage or loss expected should an outbreak of terminal weevils arise in a stand or area. Hazard is dependent on stand and site factors that are conducive to successful weevil buildup. In general, the higher the hazard, the more damage will occur during an infestation. Hazard is based on stand characteristics and climate.

Instar
The insect stage between successive moults, the first instar being between hatching and the first moult.

Risk
The probability that a tree or stand will be attacked by terminal weevils. Risk is dependent on the proximity of a terminal weevil population to the stand in question. The higher the risk, the more likely a stand will be attacked or infested.

Staghead
A major defect resulting from three or more laterals assuming dominance.


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