As a result of my studies on the larvæ of the Hispinæ, including the present and others published elsewhere, the general ideas arrived at can be summarized as follows; but I reserve the right of altering or modifying them if it is necessary in the light of further study of more material.
- 1The body is always flattened. This is in accordance with the habit of living in the mines the larvæ make in the leaves or living between leaves.
- 2Within the group the larvae exhibit a gradation of structure, principally of the head, which changes from one of well-formed capsule to a very flattened one, this modification being accompanied by consequent changes in other structures, namely, the mouth-parts, the antenns, the prothorax, and other body-segments.
- 3The legs are not always present, but when present they are flexible.
- 4Lateral processes from each segment are usually present, but they may be altogether lost; when such is the case the segment of the body is at least triangularly produced.
- 5The number of segments of the abdomen may be nine or ten, but it is debatable whether it is reduced to eight.
- 6The surface of the skin shows various kinds of structures.
- 7Respiration being important there are various spiracular devices with appropriate modifications of the parts concerned.
- 8Although the head and thorax of the pupa resemble those of the adult and the abdomen that of the larva, these structures may have their own modifications.
- 9The leaves of the food-plant, owing to the special circumstances of the mode of life of the larvae, have undoubtedly considerable influence on their structure. The physical condition of the leaves, the moisture content, the rate of evaporation of moisture from the leaves are factors which should be taken into account.
- 10Within the limits of a species the characters of the larva seem to be constant. However, there are larvæ which, although they show greater general resemblances among themselves, differing only in details, produce imagos of totally different structure.
- 11It would seem that the larvæ in this group respond more quickly to stimuli and undergo modification of structure more readily than do the adults. It may be said that the larvæ are more plastic. Therefore, in the cases where a doubtful point of relationship is to be settled more reliance should be placed on the adult characters.