Thesis (M.S.)--Virginia Polytechnic Institute, 1935. / Includes bibliographical references (leaf 55). Also available via the Internet.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references.

No description available.

No description available.

1. The pear borer is widely distributed in the eastern part of this country. 2. The abdominal cavity of the female was filled with eggs. 3. The incubation period of the eggs averaged 5.6 days at a mean temperature of 76.2 degrees F. 4. The larvae fed mainly on the inner bark and cambium of the trees, but occasionally burrowed slightly into the sapwood. 5. There were six larval stages. 6. Larger larvae devoured smaller larvae on contact with them. 7. Around 85 percent of the borers have a one-year life cycle. 8. The winter was passed by the larva in a silken hibernaculum constructed in the burrow. 9. The pupa was strongly chitinized, and the abdomen was armed with large spines. 10. The pupal stage averaged 23.0 days for the males and 17.44 days for the females. 11. The moths were most active and most of the eggs were deposited between 2:00 and 4:00 p. m. 12. On the female moth there was more yellow than on the male. 13. The average length of life for the males was 4.46 days and for the females 4.96 days. 14. In the andrews orchard 50 to 100 borers per tree were not unusual. 15. The apple is the main host plant of the larvae in Virginia. 16. About 99 percent of the moths emerged between May 15 and July 10. 17. The male moths emerged several days before the female. 18. The females had deposited 33 percent of thelr eggs when they were captured in the bait-pails. 19. The pear borer is sometimes rather extensively attacked by hymenopterous parasites. 20. The borers may be removed with a sharp hawk-bill knife in the fall or early spring. 21. In heavily infested orchards, bait-pails would be economical and quite effective in reducing the number of moths present in the orchard during May and June. 22. The common insecticidal sprays are not effective in killing the larvae. 23. Paradichlorobenzene dissolved in cottonseed oil, white mineral oil, and pine tar oil and applied to the trunks and larger limbs of the trees with a paint brush gave excellent results without injury to the tree. / Master of Science

The study covered the period August 1971 to February 1975 and was conducted in three blackcurrant plots. One plot comprised mature bushes that were pruned but not sprayed during the course of the study; the other two plots were subject to full normal managerial practices including spraying. Information on various aspects of the biology was revealed and this clarified some of the areas about which little was known previously especially for the Southern Hemisphere. Fecundity is 100 eggs per female, fertility in the field is at least 97% and predation of eggs is always less than 5%. There are six larval instars. Fungi of the genera Beauveria and Cordyceps cause up to 10% mortality of the larvae. This is the first record of the latter genus infecting S. tipuliformis. A sampling plan was developed to enable estimates of the population of S. tipuliformis at various stages to be obtained. This gave information on the distribution of stages of the life cycle within the canes according to the age of the wood. These samples also permitted the construction of life tables for three generations of S. tipuliformis in one plot and one generation in the others. Replication both in space and time was therefore achieved and the results were further replicated by considering each plot as nine separate blocks. The dispersion of the egg and larval stages was tested and found to fit the negative binomial model. A common k, kc, was calculated for the egg stage and the larval c stage. Though not vital to this present study various transformations of the raw data were investigated to see which were most appropriate in order to stabilise the variance for analyses in which such suitability is vital. The logarithmic transformation based on the k parameter of the k negative model [log (x + k/2)) was the most successful. The mortality of the eggs was quite low but a significant proportion of the emerging larvae fail to colonise the pith of a cane. This mortality is density dependent. Other mortalities including winter pruning are density independent or random. The key stage of the life cycle revealed by the life tables is the adult survival. This survival and the consequent population trend index determined from the number of eggs laid was found to be affected by the prevailing weather during the flight period especially during the last week of November and the first two weeks of December.