346 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



Fig. 49. Portion of ventral surface of eighth abdominal segment of 

 female, showing pores. ICO diameters. Page 321. 



Fig. oO. Wax-secreting peripheral spines of female ; a, external layer 

 of integument ; b, middle or main portion of integument ; c, inside por- 

 tion of integument ; d, dorsal layer of wax projecting over the margin ; 

 e, duct leading from gland to spine ; /, wax-secreting spine ; g, cylindri- 

 cal filament of wax secreted by the spine. 180 diameters. Page 321. 



II. ASPIDIOTUS ANCYLUS. 



Diaspis ancylus. Putnam. Transactiovs of the Iowa State Horticultural 

 Society for 18T7 . Vol. 12. page 321. Des Moines, 1878. 



While engaged in the study of Pulvinaria innumerahilis on a soft 

 maple in 1877, I very unexpectedly discovered tiiat the tree was fairly 

 loaded down with a species of Asindiotus in addition. My leisure time 

 being otherwise occupied, I have not been able to give this species the 

 attention it deserves. It is found on the branches and trunk of the soft 

 maple {Acer dasycarpum,) and of the linden ( Tilia curopcea) and, so far as 

 my observations have yet extended, only on trees infested with Pulvi- 

 naria innumeruMlis, but this last circumstance is undoubtedly acciden- 

 tal. A comparison of Uiese two species so alike in some particulars, 

 and so different in otheis, gives rise to many fascinating speculations 

 upon the principles underlying llieir development. Sometime when I 

 have studied more I hope lo write more fully of this subject. 



Aspidiotus ancylus approaches closely in all respects to A. nerii. It is 

 however easily separated from that species by its heavier, slightly larger, 

 and darker colored shield. The adult female differs from that of nerii 

 in having the fuitwZar pores arranged in live groups, two on each tide 

 and one in fiont of the vulva, the side groups containing from 8 to Id 

 pores each, and the front group 5 to 10 pores— the exact number varying 

 considerably in different individuals. The female lays about thirty or 

 forty eggs, with a greater or less interval betvveen each. This takes 

 place in the late spring or early summer. The young larva is less than 

 twice as lont: as broad, with tbe antenna; and legs inserted near the 

 margin, and is much less active than the Pulvinaria larva. Its beak 

 is excessively long forming a loop more than twice the length of the 

 abdomen. Its e>es are scarcely visible, it rarely moves any great dis- 

 tance from its mother, and very frequently settles down right under 

 her scale without having seen daylight at all. As soon as it settles it 

 withdraws its antenna; and legs into a position corresponding to that 

 of the Pulvinaria larva (hg. 2(5), and then gradually becomes contracted 

 until it foims nearly a perfect circle. At this time a very thin layer of 

 wax is seen to be secreted by the dorsal surface. Tliis layer continues 

 to increase steadily in thickness throughout the life of the insect. Dur- 

 ing the summer the larva moults and the cast off skin becomes im- 

 bedded in the dorsal scale, forming the dark red " umbilicus.'" Before 

 moulting the insect appears to enter a dormant, encysted state, becomes 



