73 
appearance of the insect is at first similar to that caused by the pres- 
ence of a larval Aphidius in the body of the aphid. The parasite, 
however, at length spins a silken cocoon under the aphid, and when- 
ever present can easily be found by dissection. 
The life history of this fungus is like that of E. sphcerosperma, as 
given in some detail in the account of the clover leaf-weevil, and is 
discussed at length by Thaxter in the Memoirs of the Boston Society 
of Natural History, Vol. IV., 1888, pp. 175-177. 
Macrosiphimi pisi is affected, directly or indirectly, by a large 
number of other insects, of which other writers have recorded twenty. 
These and thirteen additional species are listed below. 
& H. 
B. 
Gryllidco 
CEcanthus confluens H. 
MS. 
PentatomidcB 
Podisus maculiventris Say 
(= spinosus Dall.) 
Euschistus variolarius P. 
AcantJiiidcc 
Triphleps insidiosus Say 
Chrysopidce 
Chrysopa oculata Say 
Chrysopa rufilabris Burm. 
Chrysopa plorabunda Fitch 
Syrphidco 
Ocyptamus ( Baccha) fusci- 
pennis Say 
Platychirus quadratus Say 
Syrphus americanus Wied. 
Syrphus ribesii L. 
Allograpta obliqua Say 
Mesogramma m a r g i n a t u m 
Say 
Mesogramma politum Say 
Sphperophoria cylindrica Say 
Ichneumonido' 
Bassus l?etotorius Fab. 
Coccinellidce 
Megilla maculata DeG. 
Hippodamia glacialis Fab. 
Hippodamia convergens Guer. 
Flippodamia tredecimpuncta- 
ta L. 
Hippodamia parenthesis Say 
Coccinella novemnotata Hbst. 
Coccinella sanguinea L. 
Adalia bipunctata L. 
Chilocorus bivulnerus Muls. 
Lampyridce 
Podabrus rugulosus Lee. 
Cccidoiiiyiidcc 
Diplosis sp. 
Braconidce 
Pcrilitus americanus Riley 
Trioxys (Praon) cerasaphis 
Fitch 
Aphidius fletcheri Ashm. MS 
Aphidius washingtonensis 
Ashm. MS. 
CJialcididcB 
Isocratus vulgaris Walk. 
Pachyneuron syrphi Ashm. 
A carina, Rhyncholophidcc 
Rhyncholophus parvus Banks 
Most of these species I have studied in Illinois in their relation 
to M. pisi. Below is a summary of all that we know on the subject 
up to the present date. All these insects, concerned in one way or 
another with the clover-louse, are either predaceous or parasitic. 
CoccinellidcB. — The omnipresent ladybird beetles and their larvae 
are in this region the most efficient of the insect enemies of the clover- 
louse. The larvae in particular destroy the louse in immense numbers. 
They are by no means limited to this aphid, but when it predominates, 
the number of Coccinellidce present is a good measure of the abun- 
dance of the louse. 
