Leaf Mines 
Even empty leaf mines will frequently 
permit identification of the 
particular species, provided the host 
plant can be identified reliably. 
With a hand lens it is easy to 
establish whether or not a leaf mine 
contains a larva or puparium. If it 
is empty, a representative sample of 
mines should be pressed and dried 
between sheets of newspaper, 
preferably with the flower, so that 
the identification of the plant can be 
confirmed . 
If mines still contain living larvae, 
a part of the stem containing mined 
leaves should be kept in a sealed 
plastic bag or vial until the larvae 
have pupated. It is better not to 
pick individual leaves, as they 
desiccate more rapidly than if left 
attached to the stem, and thus they 
prevent larvae from normally completing 
their feeding and pupating. 
Puparia obtained in this way should be 
transferred with a slightly moistened 
brush to the actual rearing container. 
Vials about 3 cm in diameter and 6 to 
10 cm long with a small layer of 
dampened sand have been satisfactory. 
They require attention every few days, 
adding a few drops of water when 
necessary as the sand dries out, or 
removing any excess moisture on the 
sides of the vial, which can damage 
emerging flies. 
Healthy puparia are not normally at- 
tacked by mold, but several invari- 
ably die from other causes and mold 
then rapidly develops. Dead puparia 
should be removed before the mold 
spreads and affects healthy puparia. 
Species that pupate in the leaves 
present a problem. If the entire leaf 
or even a small section containing the 
puparium is kept for more than a few 
days in an enclosed moist atmosphere, 
mold will develop rapidly on the dead 
plant tissue, ultimately killing the 
transforming larva. Remove such 
puparia from the mines before rearing 
the adults as described here. This is 
not always easy, but with experience 
the puparia normally can be removed 
without damage. 
Mined leaves from which the larvae 
have pupated or from which puparia 
have been removed, should, of course, 
be pressed in the normal way. Empty 
pupal cases should be retained together 
with the adults that have emerged from 
them or should be appropriately labeled 
so that later the two can be associated 
correctly. 
Careful, accurate labeling throughout 
the rearing process cannot be too 
strongly emphasized. Whatever system 
of serial numbering is used, the same 
reference number or label can be used 
at six separate stages: (1) Host 
plant, (2) plastic bag or vial 
containing mines in the field or 
laboratory, (3) actual rearing 
container, (4) pressed mines, (5) 
emerging adults and empty puparia, and 
(6) any parasites obtained. Mistakes 
can be made, however carefully one 
works, particularly with large amounts 
of material, but the labeling outlined 
here, if done carefully, largely 
eliminates the possibility of 
incorrectly associating adults and 
host plants, which can be so 
misleading for future workers. 
Stems and Flower Heads 
When the stems are checked, the larval 
feeding can be readily detected if the 
stem is either cut across or split 
lengthwise. By following the feeding 
track of the larva either down or up 
the stem, the puparium normally can be 
found without great difficulty and 
should then be removed and reared as 
described here. Once a given host in 
the field is known to contain agromyzid 
puparia, time can be saved by randomly 
selecting stems that can be examined 
in more detail later in the laboratory. 
With flower heads and seed pods, first 
determine that Agromyzidae are 
present, then collect a large quantity 
for later detailed examination. If 
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