IQOl] ENTOMOLOGICAL NEWS. 25I 



DEPARTMENT OF E60N0M1E ENTOMOlOeY 



Edited by Prof. JOHN B. SMITH, Sc. D., New Brunswick, N. J. 



Papers for this department are solicited. They should be sent to the editor, 

 Prof. John B. Smith, Sc.D, New Brunswick, N. J. 



SAN JOSE SCALE. 



One of the most interesting pamphlets on this apparently over-worked 

 insect has come recently into my hands by the kindness of Dr. L. Reh, 

 its author. It is entitled " Zucht-Ergebnisse mit Aspidiotus perniciosus 

 Comst." and is an extract from the Jahrbuch der Hamburgischen Wis- 

 senshaftlichen Anstalten, XVII, 1899. It describes a series of observa- 

 tions made on scales found on American apples, and carries the young 

 from birth to the beginning of the adult stage. The observations con- 

 cerning the length of the various stages do not apply to field conditions 

 existing here ; but some of the other points seem to have escaped our 

 own students or to have been considered immaterial. 



First of all the suggestion is made that it is somewhat probable that 

 the species is parthenogenelic. The contrary has been rather assumed 

 than proved ; but on the other hand there is no proof either that par- 

 thenogenesis really does exist. The matter is of great practical im- 

 portance, because on budded nursery stock a few single scales widely 

 scattered in a large block may occur. I have known a set of cuttings 

 bought to obtain a new variety, to have just one scale so situated as to 

 make it likely that it would be budded in. Assuming this fo be a female 

 requiring coition with a male to produce young, and there is no danger 

 of infesting the nursery ; assuming the contrary, and this one scale might 

 prove the centre from which in a year or two a large area may become 

 infested. 



Larvae were obtained from two females, both of which threw off the 

 scale before reproduction commenced, partly covering themselves by a 

 dense white, woolly or waxy excretion from the sides of the posterior 

 segments. No reason is suggested for this particular proceeding ; but it 

 is noted that the same fact was observed on Aspidiotus pyri, Diaspis 

 pentagona and D. ostreceforniis. It would be an excellent thing were this 

 habit usual, as it would enable us to use comparatively weak sprays 

 effectively during the growing season. The observations made on the 

 active larva agree with those published by Howard and Marlatt, but it is 

 added that the larvae have for a few days at least the power to change 

 their location, even after the white waxy covering has become complete 

 over the insect. He noted two instances where larvae had set on an 

 apple and afterwards, two or three days later, changed their position. 

 The first of white scale is made up entirely of the w^axy filaments ex- 

 truded by the larva and is very easily removed from it. 



