seven days. Upon hatching, the minute larvae cross the leaf sur-
face with a "galloping" motion and reaching the edge, drop to
the ground. On the soil surface they may wander for a while and
finally penetrate the soil in search of tender rootlets on which to
feed. These larvae are small, legless and white, with a distinct
head pattern of yellow and gray. The color of the head, however,
is generally not as deep as that of other larvae found in the soil
along with Diaprepes.
 The sweet potato weevil is also an otiorhynchid beetle, but
considerably smaller than Diaprepes. It is shiny looking,
somewhat like a large ant (hence its specific name). Its elongate
snout and head are blue-black as well as the rounded elytra. The
thorax and legs are reddish brown (hence the sub-specific name
of elegantulus).
 The reproductive cycle of Cylas is probably not well understood
because of the cryptic behavior of the insect. The larval and pupal
phases develop within vegetable tissues and cannot be observed.
It is not known just where fertilization occurs in nature, though it
is assumed that it occurs mostly in the open. Promptly after fer-
tilzation the female starts burrowing into the plant leaves, stem
and junction point of developing tubers. A study of egg distribu-
tion within whole plants from a highly infested field revealed
that the eggs are distributed in an ascending order, precisely in
the sequence indicated above (Bonnefil, 1983, unpublished
data).
 The minute, white, kidney-shaped eggs are laid at the bottom
of shallow depressions carved by the ovipositing female in the
aerial parts or directly at the offshoot, of young tubers. It is possi-
ble that they are laid within the tunnels inside mature tubers. It
is known that the eggs hatch in about seven days, that the larval
instars sum up about three weeks, and the pupal stage another
week inside the tuber.
 One generation of the weevil lasts one month in the field or in
storage. It is suspected that the adult may live up to eight mon-
ths. It is also known to fly up to one mile in search of food. Flight
is not an important mode of dissemination, which is done mostly
through the planting of infested cuttings. It has been shown that
adults freed by cutting open a tuber or some other part of the
sweet potato plant showed no dispersive urge, but lingered
around or, at most, moved to the nearest planting. No reference
was found in the literature as to the fecundity of the sweet potato
weevil on sweet potato or any alternate host plant.


MATERIALS AND METHODS
 To investigate the fundamental nature of vagility, the two
 weevils were to be sampled according to selected biological
 criteria on their apparently preferred and two incidental hosts, as
 shown in the following scheme:
 1. Biological criteria (fecundity, oviposition, incubation, hat-
 ching success), related to Diaprepes abbreviatus (L.) reared
 and maintained on:
 a. Orange (Citrus sinensis [Osbeck]), Gereniales, Rutaceae
 b. Pigeon pea (Cazanus indicus [Spreng.]), Rosales,
 Leguminosae
 c. Papaya (Carica papaya [L.]), Violales, Caricaceae
 d. Mother-of-cocoa (Gliricidia sepium [Jacq.]) Steud Rosales,
 Leguminosae
 2. Biological criteria (fecundity, oviposition, incubation, hat-
 ching success), related to Cylas formicarius (F.) reared and
 maintained on:
 a. Sweet potato (Ipomea batatas [Lam.]), Polemiales, Con-
 volvulaceae
 b. Morning glory (Ipomea learii [Paxton]), Polemiales, Con-
 volvulaceae
 c. Bay hops (Ipomea pescapreae [L.] [Sweet]), Polemiales,
 Convolvulaceae


3. Comparisons using the biological criteria results for Diaprepes
 abbreviatus (L.):
 a. Favorite host (citrus) vs. incidental host (pigeon pea)
 b. Wild host (mother-of-cocoa) vs. cultivated host (citrus).
 4. Comparison between the vagile and the sedentary weevils or
 the consequences of vagility.
 A study of the preceding scheme showed that the vagile weevil
 was found on plants belonging to widely spaced orders, while the
 sedentary weevil was found on plants of the same order and fami-
 ly.
 In all cases, the plant hosts were arbusts or, at most, small
trees, easily found in the vicinity of the university campus. To
assure an ample supply of fresh plant material, arrangements
were made to grow the plants in neighboring yards.
 Diaprepes adults were collected at two experimental stations of
the University of Puerto Rico where the insects had been reported
in good numbers on a variety of hosts. They were transported in
plastic containers with screen covers and fed the leaves of the
plants on which they had been captured. The adults of Cylas were
carefully extirpated from the stolons or tubers of the selected
hosts.
 The plastic containers were kept cool and upon arrival at the
university were introduced in a constant-conditions chamber in
which temperature was maintained at 75"F (23.8"C) and light
programmed at 12 hours of light and 12 of darkness. The adults
of Cylas, by copulating pairs, were introduced into plastic snap-
boxes covered with adhesive black plastic to simulate darkness.
On the lower side of the snapboxes 6mm dia holes were drilled
through which 7cm-long sections of stolons would be placed,
wrapped in cotton to avoid damage. The free ends of the sections
were placed in florists' waterpicks filled with 1% sucrose solution.
 Probes for the two weevils were made simultaneously, and all
fresh plant material was renewed every three to four days. As
changes were made, observations were recorded.
RESULTS
 The main objectives of the research project were largely ful-
filled. Unforeseen difficulties could be overcome, thus a sizable
amount of original data could be gathered. An aspect was added
to the original layout which provided valuable information as to
the annual cycle of infestation of the sugarcane weevil borer. It
had been hypothesized that wild hosts carried over the infestation
from one crop year to the next (more in the case of the vagile in-
sect), residual populations surviving on the wild hosts scattered
among the cultivated blocks.
 The pattern turned out to be exactly that. In the case of
Diaprepes, mother-of-cocoa was used as a typical wild host and
morning glory in the case of Cylas. Eggs are laid by both insects in
the known manners, the larvae drop to the ground and penetrate
the soil, taking advantage of the spring rains (April, May) which
loosen the soil surface and impart humidity. The sweet potato
weevil is carried with the infested cuttings and, as the plants start
to grow, first infest the stolons and later the starting tubers.
 The criteria of comparison for fecundity, development and
longevity were chosen as follows:
1. Total numbers of eggs laid throughout the residence of the in-
 sects in laboratory;
2. Duration of oviposition;
3. Daily rate of oviposition;
4. Average duration of oviposition;
5. Percent live larval births; and
6. Total days lived in the laboratory.
 Although computer service was available for the statistical
analysis of the data, it was decided to proceed the traditional way
for the benefit of readers interested in statistical methodology.
The method followed was that of unpaired observations of un-
equal variances. The hypothesis of equal variances was tried and
then given up.


PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY-VOL. XX


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