ABSTRACT Santos, Rosemarie. May 2023. INSECTICIDAL EFFECT OF PANDAN BULB (Pandanus amaryllifolius) LEAF AND GARLIC (Allium sativum) ETHANOLIC EXTRACT AS TOXICANT AND REPELLANT AGAINSI AMERICAN COCKROACH (Periplaneta americana), BACHELOR OF SCTENCE IN BIOLOGY MAJOR IN MOLECULAR BIOLOGY AND BIOTECHNOLO. Pampanga State Agricultural University, Magalang, Pampanga. Adviser CRISTEL JOY C. MALLARI, M.Sc. American cockroach (Periplaneta americana), locally known as ips is one of the most common pests in today's homes. It is considered one of the largest species oI roaches carrying a wide range of pest-related diseases. Hence, the study aimed to determine the effects of Pandanus amaryllifolius and Allium sativum extracts as toxicants and repellents against American cockroach (Periplaneta americana). As such, the study was conducted from September to December of 2022 at the laboratories of Pampanga State Agricultural University. Furthermore, a total of (10) American cockroaches per treatment of plant extracts were used and laid out using a Complete Randomized Design (CRD) with three replicates. Data gathered such as repellency and mortality (%) were subjected to One-way Analysis of Variance (ANOVA) with Tukey's Honest Significant Difference (HSD) for Post Hoc Analysis. Findings implied that both of the plant-based extracts of the study obtained comparable results with the positive control (chemical insecticide) as determined by the repellency and toxicity studies. Among the tested treatments, T1 (Pandanus amaryllifolius) is the most effective repellent and toxicant against American cockroaches than T2 (Allium sativum). On one hand, repellency assessment using the Harborage Choice Method showed that at the end of data gathering, T1 (Pandanus amaryllifolius) obtained the highest American cockroach repellency with a mean value of 10.00 constitutes to 100% repellency rate as compared to T2 (Allium sativum), where repellency rate is at 96.7%. On the other hand, the results for Fumigant Toxicity Test implied that T1 (Pandanus amaryllifolius) has the highest mean mortality of 7.33 (73.3%), as compared to T2 (Allium sativum), which is 5.33 (53.3%). Therefore, the use of plant materials such as Pandanus amaryllifolius and Allium sativun is a viable option to combat American cockroaches. Keywords: Pandams amaryllifolius, Allium sativum, American cockroach, Insecticide.