Megaselia scalaris(Diptera: Phoridae) is regarded as a medically important insect worldwidebecause it is the source of different myiasis diseases. Therefore, it should becontrolled for human welfare and for economic reasons. Accordingly, the larvicidal activity of six plant essential oils wasdetermined against M. scalaris and their impacts on proteins andisozymes were also estimated in whole body homogenate of the third larvalinstars. The tested essential oils were chamomile (Matricaria chamomilla),clove (Syzygium aromaticum), orange (Citrus sinensis), rosemary (Rosemarinusofficinalis), spearmint (Mentha spicata) and sweet basil (Ocimumbasilicum). Results exhibited that the clove oil had the highest larvicidalactivity, LC50 is 2.38 ml/100g media, whereas, chamomile oil was theleast one, LC50 is 5.37 ml/100g media. Significantconcentration-mortality responses of the treated larvae were observed towardsall tested oils. Concerning protein estimation, the control protein content was12.80±2.68 mg/g tissue, and the oil application produced an elevation in totalprotein contents in treated larvae. This elevation was significant (p 0.05)with chamomile, rosemary and sweet basil oils. The electrophoretic studyrevealed that the maximum number of native protein bands was seven atapproximately rate of flow ranging between 0.14 to 0.72 in the control andclove, orange, spearmint and sweet basil treatments. One newly formed proteinband was observed in whole body homogenate of clove, orange, rosemary,spearmint and sweet basil treatments. The profiles of β-esterase,alcohol dehydrogenase and aldehyde oxidase showed the same patterns in bothcontrol and treated larvae. On the other hand, there was a reduction in theisozymes amount percent in the treated larvae as compared with the controlvalues. The biochemical changes in native proteins and isozymes could be usedas a biochemical indicator of toxic stress.