50 
HOP. 
great value, both from his personal observation and from having com¬ 
pared and weighed the opinions of many entomologists, and he states 
that he considers the Malaheb to be a variety of the species Humuli 
(above mentioned), and that it is common on the Sloe and Plum in 
May and June.* 
It is also stated by Dr. C. Thomas, State Entomologist for the 
United States of America, State of Illinois, that he considers the 
Malaheb (Fonsc.), i. e., the Damson-Hop Aphis, is but a variety of the 
species Humuli. f 
In all these observations I have been careful to limit them to the 
Hop Aphis, the Aphis ( Phoroclon ) Humuli, Sclirank, and its variety, 
the Aphis ( Phorodon ) Humuli, var. Malaheb, of Fonscolombe, which for 
convenience I call in English “Damson-Hop” Aphis; and it will be 
seen that in the above notes we have direct statements from trained 
entomologists of the Hop Aphis migrating from Sloe, and also of the 
Malaheb being only a variety of the Humuli. 
I do not think we can trust to the observations of non-entomologists 
not conversant with minute distinctions of species, nor aided by 
powerful magnifiers, as to special cases of transference. Therefore, 
though with regret, I have not inserted several notes ; but I certainly 
consider that the opinion of a large number of Hop-growers that the 
Fly comes to some amount on the wing from Sloe or Damson, backed 
up as it is by all the details above given, is a strong foundation for 
reasonable belief in the theory of migration. 
The great difficulty as to whether the Humuli and Malaheb are to 
be considered distinct or not rests on how far such amount of greater 
development of the frontal protuberances as exists, or is considered to 
exist, in the Humuli may constitute it a distinct species. As far as I 
can venture to form an opinion, I join with those who think it does not 
amount to specific difference. And further, it appears to me that this 
marked development of the tubercles and root-joint of the horns which 
we see on the Hop-lice in various conditions in summer is an increase 
in development on the form that they bore in early spring, as well as 
on the form of the Damson-Hop lice. 
From the latter part of March onward to about the time of the 
appearance of the Fly, I found that the Hop-lice had the frontal 
tubercles and enlarged root-joint, as figured atp. 48, J this sketch being 
a representation of large numbers sent me from infested Hop-plants, 
* ‘Brit. Aphides,’ G. B. Buckton, F.R.S., vol. i., pp. 168, 169. 
f ‘ Eighth Report of the State Entomologist on the Noxious and Beneficial 
Insects of the State of Illinois,’ by Cyrus Thomas, Ph.D., p. 70. 
J The examinations were made with inch and quarter-inch object-glasses, and, 
as mentioned before, with great care to remove all other Aphides besides those 
under consideration, and especially Aphis Pruni. 
