EXPERIMENT STATION BULLETINS. 



235 



A careful study of this material and some other at my disposal, seemed to narrow the 

 possibilities down to two species, L. armeniacum and L. cerasifex. The distinction 

 between these two species is very close indeed. They work on about the same plants. 

 Their life histories correspond closely and structurally they are about as close as could 

 be desired. 



Mr. Pergande, whose profound knowledge of this group is known to all 4 says in 

 response to a letter: 



" {Lccanium armeniacum) is more readily distinguished from serasifex before harden- 

 ing of the derm of the full grown female, when the derm is distinctly fasciated and 

 more or less distinctly covered with an easily detached pubescence or threads of wooly 

 secretion. In cerasifex the fasciae appear to be wanting and it is also much darker." 



Pig. 4. — Fungus disease of Apricot Scale, a, on Lccanium on ash ; b, on true Apricot Scale on 

 plum. Prom photograph enlarged 4y 2 times. Original. 



Of the other related species, rugosum has antennas of eight joints, with joint three 

 longer than the five following (Signoret) prunastri has antennae with six joints, joint 

 three longer than two, four, five and six (Signoret) and with the fourth shortest. In 

 rotundum the scale of the male is tuberculous while the species in hand has a male 

 scale quite free from tubercles. 



HOST PLANTS. 



The writer has found scales that at least structurally resemble the one in question on 

 maple, elm and peach, besides one very similar to it on hackberry. The scale on hack- 

 berry differs somewhat from the apricot scale in size, being considerably smaller, but 

 that may be due to the fact that the hackberry has more slender twigs, thinner bark, and 

 is less succulent, thereby affording less nourishment to the scale and consequently a less 

 vigorous growth. The writer was able to find only six hairs in the ano-genital ring in 

 the specimens examined. In order to settle the question, infested branches of hackberry 

 have been placed in plum trees to see whether the scales will migrate to the plum and 

 assume the form of the apricot scale. 



In other states the insect has been reported as working on grape, apricot, plum, cherry 

 and Spanish chestnut. 



