FOOD PLANTS. 
33 
THE ADULT. 
Length 3.5 to 5.75 mm.; breadth 1.75 to 2.75 mm. This stage is too well known to 
require particular description. The original description by Herbst is given on pages 13 
and 14. (See PI. I, figs. 1 and 2; PL IV, fig. 1; text fig. 18.) 
Mandible 
Mcaalfa 
Mandibles 
! ^Labial palpi 
Labium 
Maxillary palpus 
Fig. 18.— The plum curcuno: Mouth parts of the adult— a, and a', mandibles, lateral aspect; b, dorsal 
aspect; c, ventral aspect; d, maxillary palpus. Much enlarged. (Original.) 
FOOD PLANTS. 
The plum curculio feeds upon and oviposits in practically all 
pome and stone fruits, as the apple, pear, quince, plum, peach, 
cherry, nectarine, and apricot. Certain wild fruits are also more or 
less used, especially when those above mentioned are scarce, as 
Cratasgus, crab apple, etc. There are records of oviposition in 
huckleberry, grape, strawberry, gooseberry, currant, and wild per- 
simmon (Diospyros virginiana). There are also numerous records 
in literature of the breeding of tins insect in black knot (Plowrightia 
morbosa), which we were able to verify during 1910. Not all fruits 
used by the female for egg-laying purposes, however, furnish suit- 
able food for the growth and maturation of the larva, and from tins 
standpoint the instinct of the parent beetle is often faulty. Never- 
theless, there is evident choice of fruits for oviposition and, as stated 
by Trimble many years ago, in about the following order: Nectar- 
ine, plum, apricot, apple, pear, and quince. Tins order of preference 
nearly agrees with that indicated \yy our own observations, but 
Trimble does not include the cherry and peach, which we would 
place after plum, with the position of nectarine doubtful, as we have 
made but few observations on this fruit. 
It must not be understood, however, that in the presence of all of 
these fruits the curculio will choose certain kinds to the neglect of 
others. As a matter of fact, in orchards of mixed fruits, as phi in. 
peach, apple, and pear, all of these sorts will be freely punctured; 
but plums more so, as a rule, than the others. The insect undoubt- 
edly prefers smooth-skinned fruits, and in the case of plum, nectar- 
ine, and apricot, winch are usually first to attain sufficient size to 
receive the eggs, these are always much used. Nectarines and 
17262°— Bull. 103—12 3 
