6 
numbers (save in exceptional seasons) by natural enemies than the 
melon aphis. The usefulness of these natural enemies, of which a 
large number have been recorded, in subduing the aphides can not be 
overestimated. Garden and field aphides generally are subject to 
attack by the same classes of parasitic and predaceous enemies. The 
number of species of insects known to prey upon the melon aphis is 
about 35. The list includes many ladybirds or ‘*‘ ladybugs” (Cocci- 
nellidx),“ which destroy the aphis both as beetles and as larvee; the 
maggots of certain syrphus-flies (Syrphidze),? which consume large 
numbers of aphides; aphis lions—the larvee of lace-wing flies, of the 
families Chrysopide and Hemerobiide.* A number of species of para- 
sitic insects, chiefly minute forms of Braconide, are also very impor- 
tant checks on the increase of aphides.“ Many, too, are destroyed by 
parasitic fungi. 
The insect enemies of these, as of other aphides, keep their hosts, 
in many portions of the country and in ordinary seasons, in nearly 
complete subjection. The parasites, in particular, are most effective 
in dry, warm weather. In cooler, moist summer weather, especially 
following the same atmospheric conditions in spring, when vegetables 
subject to aphis injury are starting growth, these otherwise natural 
checks are less active, and the aphides, as a result, frequently gain the 
ascendency. 
Some of the commonest species of ladybird enemies of this and 
other aphides are illustrated in figure 3. In the ‘‘aphis year” of 1898 
the Scymnus (fig. 3, 4, 7,7) was particularly abundant in and near the 
District of Columbia on aphis-affected plants. A still more abundant 
and useful form of this class of insects is the convergent ladybird 
(ippodamia convergens Guér.), shown in fig. 3, a, 6, c. It is fre- 
« Hippodamia convergens Guér. and Cycloneda sanguinea L. are prominent enemies, 
as are also Megilla maculata De G. (fig. 3, d, e) and Coccinella 9-notata Hbst. Other 
species are Scymnus terminatus Say, S. caudalis Lec., S. cervicalis Muls. (A), 
Chilocorus bivulnerus Muls., Exochomus constristatus Muls. (H), and Hippodamia 
13-punctata L. 
Syrphus flies include Syrphus americanus Wied., Allograpta obliqua Say, Baccha 
clavata Fab. (babista Walk.), B. lugens Loew. (H), B. cognata Loew. (H), B. fusei- 
pennis Say (A), and Lupeodes volucris O. 8. An agromyzid fly, Leucopis nigricornis 
Egger, also preys on this aphis. Cecidomyiid enemies include certain undetermined 
species of Contarinia (Diplosis). 
¢ Among the lace-wing flies are Chrysopa oculata Say, C. plorabunda Fitch, C. albi- 
cornis Fitch (A), C. nigricornis Burm. (A), C. lineaticornis Fitch (A), C. attenuata 
Walk. (A), Micromus posticus Walk., and Hemerobius gossypii Ashm. (A). 
@ Parasitic braconids include Trioxys testaceipes Cress., Lysiphlebus gossypii Ashm., 
L. citraphis Ashm., L. cucurbitaphis Ashm., DL. minutus’ Ashm., Lysiphlebus sp., and 
Pachyneuron sp. A chaleis fly, Stenomesius aphidicola Ashm., has also been reared. 
The species followed by (H) were observed attacking Aphis gossypii on orange trees 
in Florida by H. G. Hubbard, those marked (A) by Wm. H. Ashmead on cotton in 
Mississippi. The others are mostly well known, and have been observed by various 
persons, as well as by the writer. 
