MARCH,
1959]
CONTROL OF LICE
3
of these calves were rather badly affected and though a large number of adult lice was not
found on their body, numerous nits and several patches of hairless raw skin were present,
particularly in the region of the neck and tail. Each of the three treatments, namely 0.5 per
cent DDT, 0.1 per cent lindane and plain water (as control) was applied on the body of
a group of three calves. About a pint of fluid was used for treating each calf. Treatments
were applied on January 12, 1956. The efficacy of the treatments in the control of lice was eva-
luated on the basis of the number of lice found in a ten minute period on the neck region of each
calf. The result is shown in Table I.
TABLE I—Efficacy of DDT and lindane treatments on the control of louse, Heamatopinus
tuberculatus, on buffaloes
Treatments
0.5 Per cent DDT
0.1 Per cent lindane
Water (control)
Average number of lice per calf found in 10 minutes
24 hours
before treat-
ment
3.3
1.3
1.6
1
0
0
0.66
7
0
0
2
Days after treatment
18
0.5
0
6.6
28
1
0
5
42
3.5
5.3
20
49
7
8.3
36.3
65
37
28.6
97
Per
cent
initial
control
100
100
*Weeks
effec-
tive
1
4
*In all the Tables "weeks effective" column shows the time before motile forms of lice were observed on the
treated animals.
Table I shows that with both the insecticidal treatments, namely 0.5 per cent DDT and
0.1 per cent lindane, cent per cent control of the lice on the buffalo calves was achieved and
that the calves remained louse-free for at least one and four weeks in case of DDT and lindane
treatments respectively. Though the re-infestation started after these periods, the population
of the parasite on the treated animals remained much lower than in the case of the controls
even until a couple of months after treatments. In about a month after treatment the bene-
ficial effect of the insecticidal treatments was marked on the calves by the disappearance of the
bald raw patches on their body and by the general improvement of their health. No sign of
any adverse effect of the treatments on the calves was noticed. It will be seen from Table I
that there was some reduction in the lice population on the control calves also immediately
after treatment with plain water but after a few days the infestation developed again. This
might be partly due to the water treatment itself and partly due to the contact of these calves
with those treated with insecticides.
Trials against cattle louse (Linognathus vituli)
In one of the two trials on cattle lice L. vituli, 0.25 per cent DDT, 0.1 per cent lindane, 0.1
per cent chlordane, 0.25 per cent dieldrin, 0.05 per cent diazinon and 0.25 per cent mala-
thion were used. A calf infested with lice was treated with each of these insecticides. About two
pints of fluid was necessary for treating each calf. Treatments were applied on April 25th,
1956. Observations on the efficacy of the treatments were made by counting as far as possible all
the lice present on the body of the calves 24 hours after treatment and at weekly intervals there-
after upto six weeks.
The results of the trial as can be seen from Table II showed that there was cent per cent
initial control of lice with each of the insecticides used and that all the calves thus treated
remained free from lice infestation for at least six weeks. After this period the calves were
not available for furtther observation.