34 MASS. EXPERIMENT STATION BULLETIN 249 



Choice of Hibernating Quarters 



The beetles apparently prefer to spend the winter under leaves rather than 

 under hay or stones, and many observations have shown them to be more 

 abundant in the spring on trees adjacent to woodland than elsewhere. Ap- 

 parently they will fly at least half a mile if necessary to find their favorite 

 cover, returning the same distance to the trees in the spring. On October 

 4, 1927, 500 beetles were liberated in a cage over an apple tree containing 

 several different types of winter covering arranged in easily accessible piles. 

 On November 27, after a thorough examination, 209 or 41.8 per cent of 

 the beetles were recovered, the majority being found under leaves, as shown 

 in Table 9. 



Table 9. — Type of Cover Preferred by Hibernating Beetles of the 

 Plum Curculio. Waltham, Mass., 1927 

 Type of Cover 



Maple leaves 

 Apple leaves 



(from tree in cage) 

 Dried grass 

 Stones 



Corrugated paper 

 Screen sides of cage 



Time Required for Development from Egg to Adult 



Approximately 55 days are requii'ed by the plum curculio to develop from 

 a newly laid egg to an adult. Cool weather, unfavorable food, and lack of 

 sufficient soil moisture may lengthen this period, while some individuals 

 develop more quickly. The averages for three years are shown in Table 10. 



Table 10. — Average Time Required by Plum Curculio to Develop from 

 Egg to Adult in Breeding Cages 

 Larva, Pupa and 



Adult in Soil — Egg to Adult — 



Days Total Days 



31.75 55.22 



30.96 55.32 



29.50 51.04 



SEASONAL HISTORY.* 



Occurrence of Beetles in Trees. 



The first of the overwintering beetles are found in the trees when the 

 blossom buds are showing pink. They are not abundant early in the season, 

 and the greatest proportion of the total number collected in any season before 

 petal-fall was 1.6 per cent in 1927. As shown in Figure 4, the majority of 

 those collected by jarring" were found between June 10 and 30, with the 



B The method of jarring referred to consists of placing under the tree two 

 cloth covered frames each 6x12 feet, with a square hole cut in the 

 center for the tree trunk, and bumping the larger branches sharply 

 with the padded end of a pole. The beetles fall to the sheets where they 

 are picked up and counted. In this work the jarring was done each 

 Tuesday and Friday morning about daybreak, regardless of the 

 weather, but it was noticeable that the beetles were jarred from the 

 trees with more difficulty when the trees were wet. 



