NATURAL ENEMIES OF THE LOCUST. 
267 
described in our First Report (p. 305), and is found in the locust egg- 
pods or near them, of different sizes, during most of the year. These 
larvre begin to transform to the pupa state early in the summer, and the 
pupa (PI. XVI, Fig. 2) pushes itself half way out of the ground in order 
to disclose the fly. These flies continue to issue during the summer 
months. As a rule but one year is required for full development, but 
there is, in this respect, great irregularity and the same tendency to re- 
tardation which we have called attention to in the case of the blister- 
beetles. We have had quite a number of the larvae remain over un- 
changed till the second year, and all that we have said as to the philoso- 
phy of this retardation in the one case applies in the other. We are 
inclined to think that future observation will show that there is a still 
further parallel, in that the newly-hatched lame of the bee-flies are much 
more active than the later stages, and somewhat different in structure. 
The three later stages of the insect may be characterized as follows : 
Larva (PL XVI, Fig. 1). — We quote herewith our former description : 
Average length, 0.50 inch. Body curved, glabrous, tapering posteriorly, swollen 
anteriorly. Color opaque whitish, with translucent yellowish mottlings, and some 
venous marks at sutures, especially along medio-dorsum. Sutures deep. A lateral 
row of swellings. Head small, flattened, dark brown, in five pieces, consisting above 
of a frontal ovoid piece and two lateral pieces of somewhat similar form, and each 
bearing near tip a minute, two-jointed palpus; beneath of two broad, subtriangular 
jaws, having forward and lateral motion, and each, also, bearing near the center, in 
a depression, a two-jointed feeler. A spiracle each side in a fold between joints 2 and 
3, and another on each side of the penultimate joint, 12. None otherwise perceptible. 
With additional material we have been enabled to examine more fully the structure 
of the head. Underneath the median elevated piece which may represent the lab rum 
we find two stout spiues (PI. XVI, Fig. 1 e), faintly notched on the outer edge, 
which are doubtless the mandibles and correspond to the two dark lance-like man- 
dibles of other Dipterous lar /ie, for they are retractile and run back into the thoracic 
joints, and remain after the other trophi are detached. The pair of feelers upon the 
upper lateral jfieces, which seem to have no motion, might then represent tbe antenna} 
and the two lower jaws the maxill* with their palpi, while the labium is shown in a , 
chitinous point visible only when the larva extends and raises the other parts. A pe- 
culiarity in the movement of the maxilla3 or the lower pair of horny pieces is worthy of 
note. They move in alternation with one another in the forward and backward, i. e. 
up and down, motion. The palpus of these lower pieces when viewed from above is, 
as represented in the figure (PI. XVI, Fig. 1 d), circular, with two dark marks indicating 
minute apjiendages. 
When the larva is fresh and plump it shows the greater swelling of the thoracic 
joints and the translucent mottlings mentioned above. Toward the period of pupa- 
tion it becomes more opaque and more contracted. 336 
Pupa (PI. XVI, Fig. 2). — Average length 8.5 mm . Color honey-yellow, but varying with 
age, the head and thorax assuming a dark color with maturity. Head narrow, with two 
sets of 3 stout, dark spines on the top, all on a common prominence, the two lower ones 
of each set connected at base ; a pair of smaller frontal spines near the base of proboscis, 
336 So far as we can ascertain, there has hitherto been published no recognizable figure 
of the Bombyliid larva. Dufour, in his articles above alluded to, describes that of 
Uombi/lius major very indifferently and gives a dorsal view which shows little or no 
relation to the larva here described, while his description and figure of the mouth 
parts fail to indicate the different pieces we have observed in our larvoe. Yet in gen- 
eral form and structure the true Bornbylius larva will undoubtedly be found to agree 
very closely with those here described. 
