Cutaneous myiasis is a severe worldwide medical and veterinary issue. In this trial the essential oil (EO) of the Andean medicinal plant species
Clinopodium nubigenum
(Kunth) Kuntze was evaluated for its bioactivity against the myiasis-inducing blowfly
Lucilia sericata
(Meigen) (Diptera Calliphoridae) and compared with that of the well-known medicinal plant species
Lavandula angustifolia
Mill. The EOs were analysed and tested in laboratory for their oviposition deterrence and toxicity against
L
.
sericata
adults. The physiology of EO toxicity was evaluated by enzymatic inhibition tests. The antibacterial and antifungal properties of the EOs were tested as well. At 0.8 μL cm
-2
, both EOs completely deterred
L
.
sericata
oviposition up to 3 hours. After 24 h, the oviposition deterrence was still 82.7% for
L
.
angustifolia
and the 89.5% for
C
.
nubigenum
. The two EOs were also toxic to eggs and adults of
L
.
sericata
. By contact/fumigation, the EOs, the LC
50
values against the eggs were 0.07 and 0.48 μL cm
-2
while, by topical application on the adults, LD
50
values were 0.278 and 0.393 μL per individual for
C
.
nubigenum
and
L
.
angustifolia
EOs, respectively. Inhibition of acetylcholine esterase of
L
.
sericata
by EOs (IC
50
= 67.450 and 79.495 mg L
-1
for
C
.
nubigenum
and
L
.
angustifolia
, respectively) suggested that the neural sites are targets of the EO toxicity. Finally, the observed antibacterial and antifungal properties of
C
.
nubigenum
and
L
.
angustifolia
EOs suggest that they could also help prevent secondary infections.