Oct. 10, 1913 
Serpentine Leaf-Miner 
69 
October, although many larvae continue mining until killed by frosts. 
Moreover, a very large percentage of the larvae in the mines are parasitized 
at this time, which greatly reduces the number of healthy pupae that 
would otherwise enter hibernation. The junior author, in an effort to 
secure hibernating puparia at Salt Lake City in January, 1912, gathered 
old alfalfa leaves and loose soil from irrigation-ditch banks where the 
mines had been common during the summer of 1911, but only parasites 
issued from this material. 
Healthy puparia formed late in October pass the winter in that stage 
in the latitude of northern Indiana. 
Hibernation takes place largely in waste places where volunteer alfalfa 
is found growing. In the arid country of the West such patches of alfalfa 
can be found everywhere along irrigation-ditch banks, fence rows, and 
railway right of ways, where it escapes from cultivation. 
BEGINNING OF ACTIVITY IN SPRING 
Adults emerging from hibernation are abroad in April in southern 
California and Arizona and during the month of May in the intermountain 
region farther north. Evidently they do not travel far before oviposition 
takes place. As an indication of this it was noticed, both in Utah and 
again in Arizona and California, that the first mines observed in spring 
were usually either confined to the foliage of a single plant or scattered 
more or less sparingly over two or three adjoining plants. The occupants 
of these mines, whether larvae or pupae, were all in nearly the same stage 
of their development, thus indicating that the eggs were either deposited 
by a single female, or, if by more than one, at about the same date. 
It was noticed, also, that the female confines her oviposition to a small 
area, usually placing only one egg in a leaf. In the Salt Lake Ba^in the 
first mines in spring were usually found clustered on volunteer plants 
along irrigation-ditch banks, where the insect probably had hibernated. 
OVIPOSITION AND THE EGG PERIOD 
The eggs are deposited in the cellular tissue of the leaf, and the process 
of oviposition has been observed by several members of the Section of 
Cereal and Forage Insect Investigations of the Bureau of Entomology. 
The female deposits the egg from the underside of the leaf, frequently 
near the margin, where she can anchor herself by hooking the tarsal 
joints over the edge during oviposition. The fly inserts the ovipositor 
into the tissues, thrusting the tip of the abdomen against the leaf and 
puncturing the tissues with her ovipositor. She enlarges the opening 
thus made by a rotary motion of the abdomen and places the egg well 
up into the cellular tissue against the epidermis on the upper surface. 
After the female has finished enlarging the opening she turns around 
and sucks up the sap from the aperture, after which she is soon engaged 
