The infecting flight muscles of adult desert locust Schistocerca gregaria with the entomopathogenic fungus Beauveria bassiana were studied. The entomopathogenic fungus caused mortality percentages 85.56 and 81.11% in 5th nymphal instar and adults after 15 days of treatment; also, LT₅₀ was 9.17 and 10.07 days.
The histopathological studies of treated muscles showed that the nucleus, mitochondria, myofibrils and vacuoles were highly deformed. Estimation of total carbohydrates, total lipids and total protein were carried out. The results showed that the Haemolymph content of treated insects was highly affected and all the studied parameters were lower than in the control insects. The decrease in the Haemolymph contents increased with increasing the post-inoculation period.